I would take a look at the Tech Section of Club4ag. They have some great articles about the different engines.

Personally, I think you may have a difficult time putting a 20v into a Corolla for 2k. At the very least, you are going to need to change water lines, the distributor location, the header and the engine management. That is in addition to the purchase of the engine. If I were you, I'd build the 16v. You will probably be looking at less power than a 20v, though.