Edelbrock 500 cfm vs 600 cfm

[Tx Firefighter]

I'd go with the 500 myself. You likely know this, but the SP2P was an intake Edelbrock made in the 70s designed for improving fuel economy. It was not made for performance improvements over the OEM intake. Those were the oil crunch years and folks were feeling the gas prices so Edelbrock made these to try and offer improvements on the economy side. For this reason, the design uses very small (but efficient) ports. For that reason, I'd choose the 500 cfm unit.