Stock intake vs performer?

AIV,

Porting and gasket-matching the Performer #2176 will be beneficial, especially for
higher RPM power {+4500 RPM's}.

The only negative, is that the Performer 'runner-ports' are not as big.

I think you can make the Performer 'close' to a 'stock' 1971 340 Cast Iron Intake
with massaging, but it will 'not' outperform the stock factory unit.