For some cams there are vernier adjustable timing, usually about 1/4 degree per pin slot
For pulls you want a small carb and a long inlet tract
For revs you want a big carb, big short valve openings and a short manifold with a long air ram.
Then you need to extensively build up the heads so you have discreet paths for the inlet & exhaust, then grind out the combustion chamber so it is 100% over the piston.
move the spark plug so it is about 1/3 the diameter distance from the closed side of the cylinder to get most of the combustion happening over the piston.
Even then 7000 RPM is the best you can hope for which you can not do with a std piston , conrod or crank.
Serious Hp will require ball & rollers on the crankshaft & steel con rod