Looks good in theory to me. Can’t tell you about in practice however.
Maybe. But it is usually simpler to buy the replacement kit for what you have now.
I’ve replaced the innards of our three toilets several times over. The handle is the easiest thing to fix. Definitely take the one you have now with you to the store. We have three different types of handles, one quite odd. Replacing the handle usually involves only unscrewing it from the tank and then screwing the new one in and attaching the chain. (Mark where the chain hook is also so you get the same length from the new one.) You don’t even have to empty the tank.
Replacing the innards is not hard, it just isn’t necessary.
After studying all the toilet parts at Home Depot, I wound up buying just a handle replacement. I’ve looked inside the toilet tank enough that I think I got one that will work.
The only reason I wanted to replace all the innards is because of the 30+ years of that iron-saturated yukky water. I thought it would be nice to have new toilet tank innards. But, if it works, why bother, right?
I will try it when I get home. 
30 years?? That’s impressive. I have to replace mine every six months or so… And what bolts are you guys talking about? I’ve never had to replace any metal bolts when I replace the innards.
Why? What happens to the parts?
If your innards are made of iron, definitely keep them. The new ones are plastic, and don’t last nearly as long. Mine go for longer than six months - easily five years - but still go. And the parts are sensing what I type and are preparing to fail, I just know it.
Your parts might also be nonstandard, which could be a problem. The people who owned our house before us bought closeouts for everything, and one of our toilets has a non standard hole in the bottom. We finally got things to work by using underwater caulk. You don’t want to go through something like that.
If it ain’t broke, flush it. That’s what I say.
All I know is, don’t believe the box at Home Depot when it tells you that the parts are “universal” and will “fit any toilet.” That may be true if your toilet is less than ten years old. But my circa 1974 crapper required a visit to Ye Olde Plumbing Arcania Shoppe to find parts that would fit it. If I’d known I was in for a “National Treasure” type scavenger hunt in the first place, I’d have saved myself a lot of time and just gotten an all-new terlit.
I’m home but don’t feel like dealing with the toilet thing tonight. Too tired. Lots of good comments here.
Re “they don’t make them that way anymore,” when I was married the first time, my husband bought me a portable dishwasher for Christmas 1973. It’s the kind you roll over to the sink and hook to the faucet. It went on many moves with me and through several relationships and into a marriage, to this house, and then into widowhood. I finally had to replace it in 2005. THIRTY-TWO YEARS LATER. The shelves had begin to disintegrate (did I mention the really bad well water???)
I bought another portable and the guy at the store said, “Don’t expect this one to last as long as your first one. They don’t make them that way anymore.”
Ah yes… in my case the assistants are of the feline persuasion.
I have to do this very thing to the downstairs toilet over the weekend (it’ll be too freakin’ hot to do anything else outside, thank you very much central Indiana weather!!), and I have absolutely no doubt that while the boy kitty will be less than intrigued, the two ladies, especially the kitten, will want to be front and center for all the goings-on, ‘helping’ me as they’re so fond of doing on so many home repair projects.
Maybe I can lure them into the garage for the duration of Operation Toilet Innards Replacement. 
[QUOTE=Voyager]
Your parts might also be nonstandard, which could be a problem. The people who owned our house before us bought closeouts for everything, and one of our toilets has a non standard hole in the bottom. We finally got things to work by using underwater caulk. You don’t want to go through something like that.
[/QUOTE]
I was once in hand-to-tank combat with an amusingly named American Standard toilet that was the epitome of non-standard. Everything about it was so weird with respect to what’s on the market now that I ended up replacing the entire toilet.
One nice thing about toilets is that they are so basic and simple that you can buy a perfectly usable new one for about $70 in case things go horribly wrong, and unless you want something absurd like a Kohler Hatbox that costs more that most people’s first car, better models are still not too expensive.
You’ll notice the quality when you buy a kit from Lowe’s or Home Depot. The float valve is made from cheap plastic that cracks and leaks easily (not on to your floor, but inside the tank). This isn’t a problem while your float value is still functioning, but the water cut-off valve will eventually fail and you’ll have a constantly running toilet. I have one particular toilet that this seems to happen on every six months. I have another that the valve has lasted for four or five years.
On a positive note, once you’ve replaced the innards a couple of times, it become a five-minute job.
Follow up report:
I bought the handle with the lever-thing attached. Mysteriously, I still didn’t feel confident about my ability to install it, so when my house cleaning guy came, I asked him to do it, as he seems fairly handy. When he got ready to leave that day, he gave it back to me and said it didn’t fit-- the connector on the thingie was a different size from the hole in the tank or something… I didn’t really get what he said. The upshot: I would have to buy a different handle; this one didn’t fit.
So later I went in the bathroom and studied the handle assembly. Immediately I saw that the lever was attached to the handle in the wrong direction for that tank. The handle I bought was for a toilet with the lever on the right side (as you face the tank) and mine is fitted on the left side. But I figured there must be a way to change the orientation, and sure enough, there was.
I flipped the direction, and inserted the handle into the hole in the side of the tank where it fit perfectly, manually tightened the plastic nut-bolt thing on the lever part, attached the chain to the end of the lever, and it flushes fine.
Lesson learned: I can figure stuff out. 
Still trying to figure out why I felt so daunted by this. 
often times it is good to look at a problem. think about a solution. then let it not be a constant thought. look at the problem again. go seek some solution possibilities like find parts at the store. new challenges and the anxiety than can occur can inhibit your full creative thinking.
Good advice. It’s true that anxiety inhibits clear thinking.