the following postings suggest you can swap a 4g61, but it doesn't mention the 4g63:
http://www.hyundai.cia.com.au/ubb/Forum4/HTML/000018.html
you might also find it interesting to wander around:
http://www.rpw.com.au
for example in their discussion of the 4g63, they say it can easily handle over 400 hp.