I'm looking for advice on ignition timing of my pump-gas 451 with big cam (272@.050), currently iron headed 10.3:1 but soon to be aluminum 10.6:1.
Currently I have 22 initial (starts to fight the starter hot at 24-25). Total is 36, trying to remember the curve but think it's all in by 3000. FBO adjustable limiter plate on a stock Mopar distributor.

Also running ported vacuum advance. FBO likes manifold vacuum, but it only idles around 7-8" at 1100-1200 which won't pull the can in much if at all.
FBO can sell me a can that is all in at 8".

Since it's mostly street driven (3.91 gears), locked-out timing will not only be too advanced at low speed part-throttle cruise, but also create a hot-start problem.
Cam definitely wants more than 22 to idle the best.

What I'm thinking of is one light spring and one heavy spring with a loop. So I can crank it at about 12 degrees, and have it immediately advance once running to the start of the heavy spring, 26 or 28 degrees maybe? And re-position or remove the limiter plate so total is still 36, of course.

Or, leave the distributor where it is, but get the light-spring vacuum advance canister and hook it up to full vacuum, which will raise the idle timing into the 30's but drop when I start off.

Thoughts?