Valve seals

[Accelo]

I guessed at .008 for the deck clearance. Your closer to .045 deck clearance. Then add the gasket thickness and you are closer to .085 as the quench area.

I would use the thin steel gasket on the iron heads for sure.
Quench should never be less than .035-inches.
Standard head gaskets typically have a compressed thickness around .040-inches.
If the pistons were at deck height you would have a perfect quench with a composite gasket.

"The quench" effect causes turbulence in the combustion chamber as the piston comes up to TDC. "Good" quench reduces an engines tendency to ping. Also, the space is so small in cannot support combustion, this also reduces the tendency to ping.

Roughly over .060"-.080", the quench effect stops, that area is just another part of the combustion chamber.

I think you made a good choice. If you had all the numbers your compression would likely be in the 9:1 (nominal range).

BTW Effective dome volume for your motor would be the CC of the valve dimples in the pistons. This would be a negative number. Positive only if you have a piston dome.

Likely this is just too much information. Use the thin gasket and enjoy you new motor.
Cheers.