read through this thread, there are a fair few ideas tossed around. i ended up putting it in the too hard/im poor/lazy basket. there is no such thing as a simple engine swap (generally) and to be honest its a hunter lol, it took me a while to accept that. i seriously considered supercharging it, would work out cheaper, and be pretty radtastic i feel. then i realised im a poor student with nill fabricating skills haha.
but like flawless said, give it a half decent tickle and you'll be surprised. i know i500gt has a bloody nice set of twin carbs for a hunter lying about as he has my old hunter and they were spare. get a nice cam regrind, lightened flywheel, exhaust.....you might be surprised