Im with Duncan you dont need a big stroker or bucket loads of grunt.
You need massive corner speed to be at the pointy end, after watching far to many in car laps and recorded races lattely the quickest cars are carrying far more corner speed than the others but the outright acceleration was nothing that a 400Kw GTR could not acheive.
Unfortunatly to get a GTR cornering like a space framed calibra is a massive massive ask. Even if you have bulk grunt and limitless torque your not going to catch the chev in a straight line because he exited with 30Km/h more speed than you did.