I would think that if you went along the lines of the combat guys and with their favorite (cheaper) engine would be your best bet.

To serve the purposes for creating the club racer, decide on a cheaper readily available engine. The LA 15 would probably be the least powerful choice but if it will pull the T6 and everyone has the same engine, it would probably be OK. I would try to stay away from the expensive engines because it is a club racer and the idea is to have something cheap where everyone will participate.

Enjoy,

Jim