HELP timing advance on 2.0 liter T 1969 ???

[Babyanais]

Hello

i have an engine 911 2.0l T 1969 rebuilt . i have weber 40 idtp carb with cdi box bosch, pertronix ignitor and flame thrower 2.

My engine is rebuilt like original expect pistons, i put 6 Je pistons with more ratio
compression 9.5:1 than origin 8:1 but same diameter like origin 80mm.


Which value do i put at the distributor at idle ?
the value for a origine 2.0l T is TDC at idle.

With these pistons do i put advance??

THANKS FOR YOUR HELP