350 SBC Nova Motor

You say the motor is built for high revs So,
Basically there are two things that could limit its speed, Timing and carb.
For your engine timing will need to be prety far advanced, something like 12 to 18 degrees before advance is added. (not sure how much myself)
If you have a timing problem, The motor will sound fine but simply not have the power it should.
If it's carb, you should be hearing some noise from the intake if it's lean, and from the exhaust if it's rich.
any crackling sound in the intake of a GOOD motor (no bend valves) will tell you that there is not enough gas for the air going into the motor.
a crackling or stettering sound in the exhaust should mean too much fuel.
anyone behind the car should see black smoke too.
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Good luck.