So now we're talking automatic drag cars are we?
Old school carby fed V8s will idea high yes. New EFI ones with big cams will nearly idle back at standard idle. Obviously you're showing your severe lack of knowledge here on all things IC related.
Car at 6000 RPM making 300KW is making more torque than youre RB26 that's pushing 380KW at 8000RPM...
Don't need to rev an engine to 8000RPM if it's making more torque down low... It's all about area under the curve... In power band at 2000RPM and revving to 7000RPM is plenty for me... That's a 5K power band... You example only has a 3.5 to 4K power band... And you need to wind it up a bit before you reach it...
The RB20 can't take the head if any other RB without serious custom work to make it fit.
Bore size on the RB is different to a 25, 26, and 30.
Swap hole engine, or swap the whole car.
I've never yet managed to get a car to get firm brake pedal by repeatedly pumping the pedal while the engine is running.
Reason... The motor keeps sucking the master cylinder into vacuum.
If you're braking and then do a big down shift so you go from low RPM to high RPM you'll actually feel the pedal sink a little as the engine sucks into a deeper vacuum.