This has to be the most pointless thread on the forums right now.
For the money, the most drivable setup will be a basic RB30 with an RB25 head on top and a highflow RB25 turbo.
EDIT: I can just see this happening "Hey nice car, whats that an RB20 in there?" "Nah mate, RB24! Its got custom pistons, mismatched crank and rods, heaps of money spent on the head, cams, expensive turbo and manifold" "oooooh ok, well my stockish RB25 will smash that and its standard bottom end" "yeah mate but its not unique like my RB24" "yeah you're right, its just faster instead"