I’m willing to bet it was a 3270 then. Almost all the DEC units have reasonable (by modern standards) case-to-screen ratios. (I have a DEC 420 that I use for my home linux server, which is stashed in a closet out of sight.)
I think I used one of those as recently as 1998. Along with an amber text-screen monitor. Did it have a key on it named “Clear Screen” or some such? Printing company I temping for had an ancient ancient database program and I had to input figures… the processor must have been something like 500 KiloHertz, you’d type six characters and it would take it several seconds to catch up. Each line of data consisted of several field values with tabs between, and if you made an error the whole line had to be deleted. (and if you missed an error every line subsequent to the line with the error had to be nuked as well). I got quite a reputation for WHOPPING out the chars and tabs for an entire line and then waiting for the entire line to catch up and be accepted as data input, it was the only method for attaining tolerable data input speed.
That’s what I use every day, model M, dated “19NOV86”. Love the feel, nice and solid. Only downside is no Capslock or Numlock lights, but that’s minor.
The keycaps come off easily too, so instead of “asdfgh”, I have “6sdfg[PageUp]” 
Y’know what this thread is doing to me? One of you suckers needs to invent a keyboard that’s the unholy love child of a Logitech G15, an IBM Model M, and a Microsoft Natural Multimedia (what I type on now).
Because I want a gamer console and macros and usb hub, buckling-spring keys, and the particular ergonomic curve of this keyboard that’s the only one that doesn’t make my wrists feel like stabby.
1998 was actually the year I started using it, and did so through 2003. I don’t remember if it had a clear screen key, but I want to say it did. I remember waiting for the lines on the screen to catch up with my typing, though I could go back a few Tabs if I needed to make a correction. Once everything on the screen looked okay, I’d hit PF13 to submit it. The machine I used was shaped kinda like this (crude MS Paint). It was probably a little bit taller and a little bit longer, but I suck at drawing things.
I’ve been looking up some pictures, and I think you’re right. Aside from some very minor cosmetic differences, this is it. I guess it’s kind of telling that every picture I’ve found of this thing is in black and white. 
Ah, the true classics.
I hate clicky keyboards. Haaaaaaaaaaaaaaaaaaaaaaaaaate theeeeeeeemmmmmmmmmmmmm!!!