You can't really answer that. Being able to get a starlet competitive is going to be hard enough, let alone building one to 450bhp with response. Half the people dragging our cars don't run that much let alone a track focused one. Look at JAMs car, that was sub 1min round Tsukuba with circa 200bhp. Power isn't the be all and end all. Spend your money on the chassis and aero. You'd do better in a 240bhp car on a standard lump with £4000 spent on the chassis, rather than spending £4000 on the engine and not a lot on the actually chassis setup.
Then class, well you decide but if i put an EP into it, not pro lol. Id go in the Pocket Rocket class.
Haha this made me chuckle