Vacuum advance does not do anything at idle. It's for part-throttle acceleration and cruise only. Under full throttle, you have mechanical advance alone.
The way you were describing where you were getting detonation, you should probably replace one of the light springs in the new distributor with the lighter-of-the-two from a stock distributor. That would slow down your rate of advance. As far as how much advance you get, that's locked into the way the distributor's built. The only way to change it is to modify the slots for the flyweights; shorten for less advance and lengthen for more. Shortening requires welding. You can also adjust the rate at which the vacuum advance pulls in by adjusting it through the vacuum port with an allen wrench; again you can't change the amount but you can change the rate. However, there were a multitude of different canisters made with a different amount of pull. The amount (in degrees of advance) is stamped right on the arm on all the factory units.
Have you tried adjusting the secondary air doors yet? It sounds like they're opening too fast. Since there's no accelerator pump on the secondary side, if you stand on it and they drop open too quickly there's not nearly enough fuel for the added air. If they're loose enough, you'll get a port stall in the carb where it will just lay down and stay down until you release the pedal. The vacuum signal goes to nil and there's no other means to pull fuel past the metering rods.
The way you were describing where you were getting detonation, you should probably replace one of the light springs in the new distributor with the lighter-of-the-two from a stock distributor. That would slow down your rate of advance. As far as how much advance you get, that's locked into the way the distributor's built. The only way to change it is to modify the slots for the flyweights; shorten for less advance and lengthen for more. Shortening requires welding. You can also adjust the rate at which the vacuum advance pulls in by adjusting it through the vacuum port with an allen wrench; again you can't change the amount but you can change the rate. However, there were a multitude of different canisters made with a different amount of pull. The amount (in degrees of advance) is stamped right on the arm on all the factory units.
Have you tried adjusting the secondary air doors yet? It sounds like they're opening too fast. Since there's no accelerator pump on the secondary side, if you stand on it and they drop open too quickly there's not nearly enough fuel for the added air. If they're loose enough, you'll get a port stall in the carb where it will just lay down and stay down until you release the pedal. The vacuum signal goes to nil and there's no other means to pull fuel past the metering rods.