340 with edelbrock heads overheating

3
Rusty I have a couple of questions about this.
Generically, would 12 degrees of initial timing be about right?

Second, if he has closed chambered heads, wouldn’t those be more efficient and need less timing? Initial or total?

He didn’t mention if he has 340-specific-edelbrock open chamber heads.

Does the aluminum affect timing?

I would have thought more efficient heads need less timing. Thanks for your wisdom!!

@RustyRatRod
340 specific heads