There was a Golden Age superhero who merged with the ghost of his dead brother to gain superhuman strength, invulnerability, & flight powers.
What was his name?
Details?
Have his stories been re-printed in a TPB?
Links to images would also be helpful, thanks. 
According to Keltner (warning: PDF), which is the authority in these matters, Captain Triumph first appeared (and got the cover) in Crack Comics #27 (Jan. 1943) and every issue thereafter.
Most if not all of those issues are available to legally view or download at The Digital Comics Museum. They’re very cautious about ensuring they only provide material that’s legal to distribute, so you should have no worries on that score.
–Cliffy
Wow, there’s a lot of really obscure comics over there. I never realized how many romance comics there were. Must have been more girl readers back in the day, because I can’t imagine boys from the 40s or 50s reading those things.
Wow. What an interesting origin story; I don’t think I’ve seen that one used anywhere else (which is kind of amazing). Considering how much comic book writers like to recycle old ideas, I’m surprised no one has tried to reuse this one.
Well, there’s the 3-D Man, who misses it pretty close.