Some of the smog era cars used like 12º or 15º BTDC. Even on those cars the scale on the engine only went 10º BTDC to 10º ATDC so you had to either use a timing light with an adjustable advance built into it or put a timing tape set on the balancer.
I would strongly suggest getting rid of the points. If the dwell is not set properly on the points first, you can't properly set timing. Plus the points require more frequent maintenance than an electronic ignition would. So you want to set dwell, set RPM then set timing with vacuum disconnected.
There are really three factors to consider when setting timing:
1) Base timing - this is what you are setting with the timing light.
2) Vacuum advance - On a stock distributor this is a fixed function, but on the Mopar conversion kit the vacuum advance is adjustable so you can dial in more or less. You want ported vacuum, like at the base of the carb where there's no vacuum signal at idle and vacuum present when RPMs increase. Normal engine vacuum is the opposite.
3) Mechanical advance - The distributor will advance timing as the RPMs increase. This is why you must set RPM speed before setting base timing. This advance is fixed based on distributor design but can be modified by changing the springs in the distributor.
You may want to verify that timing is advancing as it should when RPMs increase and when vacuum is applied to the vacuum canister on the distributor. I've seen old distributors where the advance is frozen and they will backfire under throttle.
If the engine is stock, I'd tune it to the 1971 specs. If it's modified, the best way I've heard it explained is to set timing so that with mechanical and vacuum advances you have a certain advance at a certain RPM. I can't recommend the best for your combo because I generally have only ran stock engines.
I would strongly suggest getting rid of the points. If the dwell is not set properly on the points first, you can't properly set timing. Plus the points require more frequent maintenance than an electronic ignition would. So you want to set dwell, set RPM then set timing with vacuum disconnected.
There are really three factors to consider when setting timing:
1) Base timing - this is what you are setting with the timing light.
2) Vacuum advance - On a stock distributor this is a fixed function, but on the Mopar conversion kit the vacuum advance is adjustable so you can dial in more or less. You want ported vacuum, like at the base of the carb where there's no vacuum signal at idle and vacuum present when RPMs increase. Normal engine vacuum is the opposite.
3) Mechanical advance - The distributor will advance timing as the RPMs increase. This is why you must set RPM speed before setting base timing. This advance is fixed based on distributor design but can be modified by changing the springs in the distributor.
You may want to verify that timing is advancing as it should when RPMs increase and when vacuum is applied to the vacuum canister on the distributor. I've seen old distributors where the advance is frozen and they will backfire under throttle.
If the engine is stock, I'd tune it to the 1971 specs. If it's modified, the best way I've heard it explained is to set timing so that with mechanical and vacuum advances you have a certain advance at a certain RPM. I can't recommend the best for your combo because I generally have only ran stock engines.