Good luck finding an SiR, Euro-R, or Type R in the United States! Especially one that is willing to give up it's engine.
Actually the fist place I would probably look would be local salvage yards. They may have a wrecked Prelude (preferably wrecked in the rear of the car, not the front.)
Then my 2nd place to lookwould be online.

 

Technically wouldnt it cease to be an Accord if it had a prelude motor in it? wouldnt it then be a hybrid (Not as in gas/electric but in the merging of two different cars.) Im under the impression that the engine is the heart of the car. Change that and it becomes a "different" car. As in the case where a guy got a heart transplant, where the heart was "donated" by a monkey. He can no longer say he is 100% human.

 

So if a man got a heart transplant and the heart was "donated" by a woman, does that make him no longer 100% male?
It's an Accord. Pontiac GTO's have a corvette engine in them. Are they really not 100% GTO? Some Honda Oddesy's have the F23A1 from the 6th gen accord too.

I do get what you are saying though. I'm just making discussion. Try taking an H22 swapped accord to a Honda dealer if you have a problem! I bet they would be like "WTF is this?"