Going drag racing? You might need that extra weight up front to keep the front wheels on the ground?
You'll need the CORRECT pulleys for the components as they were different diameters for a/c and non-a/c cars. Otherwise, run the alternator from the water pump and crankshaft, just as the belts now are, just get shorter belt(s) for the alternator. Using the non-a/c alternator belt as a guide to start with, as to length. Have any friends at an auto supply that still carries a selection of belts?
Otherwise, for the shadetree method, run a cord around the pulleys when the a/c compressor is removed. Add, probably, abt 1-1.5" to that length to allow for the belt riding higher in the groove than the cord does. Use that for your initial trial-fit length of the alternator belt.
Just some thoughts,
CBODY67