Looking for a little advice on the timing numbers I just pulled from my 73’ Duster (backfire issue)

You likely have a bone stock "smogger" distributor with a very long advance curve. What you need to do, to start with is to determine the curve vs RPM and then set out to to make it a more performance curve

There are a number of ways
1...But a performance distributor, preferably with an adjustable advance
2...Recurve your old one by finding and changing springs, and by brazing and filing the advance slots to limit advance
3...Buy the FBO advance limit plate kit

There are a number of opinions on just what that advance should be, but with a stock cam, 8BTDC is a start. Make sure that it is not OVER advancing however

Be careful of fancy timing lights. They are known to be trouble with stuff like MSD, and in my years i"ve seen a few that just plain were not accurate.

Also be aware that the traditional manuals list the dist. curve in DISTRIBUTOR degrees which are double at the crank. AKA 10 in the distributor is 20 at the crank