None of the jet/rod combinations mentioned mean anything without a carburetor part number. I'm guessing that you are using a later model Chevy carburetor with "M" series primary metering rods?
Mixing/matching parts is a complete guessing game unless you are using the same basic units (SMAB, for example with the SAME size main airbleeds).
Stomping on the throttle has literally NOTHING to do with the primary jet/rod combination, provided it's pretty close for what you are doing and working well, etc.
The players for that deal are the accl pump (I would install one of our pumps with new springs), power piston spring (to a minor degree), secondary plastic cam/spring, hanger height, metering rod used, and the unloading rate of the pull-off (dampens secondary opening). Further players in the deal are POE, spring tension, and location of the POE holes in the airhorn.
In many cases the "falling on the face" deal goes right back to the accl pump, not enough pump shot to help overcome a lean condition, combined with a worn secondary cam, weak spring, and pull-off not the rate rate or out of adjustment (too much play on the linkage).
In any and all cases, BEFORE tuning with hangers and metering rods, get the "basic" stuff right first, then tune with rods and hangers, if/as needed......Cliff
