Will it fit? Underdrive is achieved by either making the crank/main (drive) pulley smaller or the accessory (driven) pulley larger than the original diameter pulleys or both. The set on my car when I bought it had a smaller crank pulley and a larger water pump pulley. When I had the supercharger installed I didn't want to spin it too slow reducing boost so I bought a stock crank pulley. It wouldn't fit. There is not a lot of clearance and the larger stock crank pulley hit the larger underdrive water pump pulley. Out of frustration I bought an electric water pump to replace the underdrive pulley.
The stock crank pulley might not fit without changing the water pump pulley.
ProCharger P-1SC, 9 psi, STD 396/383; Uncorrected 388/375; SAE 383/370.
USAF 1969-1973,1980-1996: Vietnam veteran. Aircraft maintenance. R & D, ICBM Operations.
Also own: 1997 Harley FXDWG, 1998 F-150, and 2002 Corvette LS1