If you didn't need to worry about cost or availability, what would be the best (<610cc) engine. Not worrying about fuel ecnomy, My thoughts are either V6, V8, or V10. If I was worrying about fuel economy, I would go with a V-twin or V4. I know everyone that has ever expressed any interest in FSAE has thought about using something other than a Honda CBR600RR engine. Also, include some reasons (other than badass factor) why you would choose that specific setup.
This isn't proposed for people to bring up logic in this; this is all just because I want to hear other peoples opinions on this. WWU is the only place to ever make any of this come true.
If you want to include transmissions, the V8 and V10 would be longitudinally mounted and have 8-speed tranaxles. The V6 and V4 would be longitudinally mounted and have 6-speed transaxles. I would also slap some turbochargers and superchargers on there. And maybe an anti-lag system just for the sound.
THis is all pipedreams, nothing real. At least keep it feasible though(I would prefer to leave out the ridiculous V200 derived from 3cc model plane engines that is inevitably mentioned on engine threads).