I don't know about the 88-91 Prelude B20A blocks being peices of shit, I read some where in an article that a person from spoon said the worst block to do a V-Tec head conversion on was the B20B from the CRV's, due to some sort of problem with the bottom end, it doesnt mean they don't work, but i'm just sayin for the sake that the B20A is not as bad a motor as u say, as for the prelude motor with a B16A head it has been done and it made the same tourque as a stock b16a motor, but with a dead cylinder, so imagine what it would have done it it had all 4 working correctly, the original site that did the B20A/Vtec was
www.ludespeed.com but unfortunaly he does not have the site up at the moment, when it comes back online you can read the outcome of the lude-tec motor. By the way, this is also something i was going to do when I had my 88 Prelude.