Either hit up a junk yard for a used 4G63 ... or join a another DSM forum where 4G63's are more prevelant and post up what all you are looking for in the WTB section and you are bound to get some hits. I'd rebuild the motor myself and send the tranny out to a speed shop if I were you. You are undertaking a large project, I hope you have experience and know what you are doing.

What motor does your Sonata have in it now? You might have to change motor mounts and everything .... :eek