my first flathead project need some advice

[scooder]

The advance should be limited by the slots in the advance plate where the pins stick through for the springs to anchor on.
The loadamatic ignition will never work correctly without the correct carb. The vacuum port on the correct carb is a mix of throttle plate and venturi vacuum signal. Not the same as ported or timed vacuum. It's a much weaker signal.
Guessing your vacuum line from the ignition goes to manifold vacuum, judging by the fact it comes in to fast.
No you can't really modify a wrong carb to work with this ignition easily, maybe not at all.
Your real options are, get the correct type of carb or change the ignition.
Martin.