LoL.. it's very very easy to make a case for the 4g63 vs. a rotary engine. The 3s platform you are bent on shares basically nothing with the 4g63. The only prob with the 4g63 that comes to the top of my head is that Mitsubishi has not been able to build a tranny to hold the power it can make....of course that's not the motor's fault.
I've actually been looking for an FD to swap a 4g into as well....
Hopefully though, i'll get my hands on a 240/260 first so i don't have to worrry about smog.