Timing Question
I have used the vacuum gauge instead of the timing light to try and set the timing also and even at highest manifold vacuum I am still having the same problem
so at the highest vacuum reading, how much initial timing does it show (at idle)? Now bring the rpms up until all the mechanical is in (you mentioned at 2200 rpm) to make sure just bring it up to 3000 rpm, now check with your timing gun, how much timing does it have now? This should probably not exceed 34-36 degrees. The fact that you have enlarged the weight slots means it is allowing too much mechanical timing, I think that is where your pinging is coming from.
Since you changed the ignition system, are you sure it was all done correctly, meaning no electrical issues (wiring), cracked distributor cap (like mentioned), faulty ignition wires, wrong coil, etc. Do you have the correct ballast resistor hooked up?
You mentioned earlier that you aren't running a vacuum advance, but in a later post you mention it is hooked up to the ported side on the carb. So are you running the advance canister or did you block it off?
When you set the timing it has to be done with the vacuum advance disconnected and the port that it was connected to blocked off.
Let us know what timing numbers (for initial and full mechanical) you got with the highest vacuum at idle with the vacuum advance disconnected.