Stalling

Sorta sounds like you're flooding. Could be a ruptured power valve which will let raw gas continually run into the intake. Power valves on older Holleys are sensitive to backfires & will tear. It's such a problem, Holley modified its whole line of 4 bbls a few years ag to include a ball-check valve blocking backfire pressure spikes. Reformulated O2-carrying gas attacks all rubber & viton fuel components, and you may have lost the fuel pump check valves, basically running the car out of gas as the float bowls empty at higher engine speeds, or the viton-tpped float valves may be leaking which would flood the motor. Finally, the distributor drive gear roll pin sometimes only PARTIALLY shears, retarding the timing 10 or so degrees and causing hot, crappy running. Don't just check for a roll pin tip at each end of the gear hole- check that the two ends are in line! Let me know which of my guesses it was....