If it may help a little, below are pics of the 1937-40 216 domed piston and the 1941-53 216 flat top piston to show a comparison. In looking through the 1929-53 Chevy Master Parts Catalog, the head casting and the casting design changed between 1940 and 1941. 1937-40 216's used head casting# 838773. 1941-49 216 & 235 and 1950-53 216's used casting# 3835517.
A description of the cylinder head assembly from the 1941 Chevy Shop Manual (pg 161) says:
"The cylinder head has been completely re-designed, increasing the compression ratio to 6.50 to 1, and the horsepower to 90. At the same time the possibility of detonation has been decreased. The combustion chamber has been especially designed for use with a flat top piston that provides exceptionally compact combustion volume on the exhaust valve side where the spark plug is located."
"On the inlet valve side the head is machined so that, except for a shallow recess in which the inlet valve is located, the bottom face of the head over the piston is flat and is separated from the piston top dead center by the thickness of the cylinder head gasket only."
FWIW, I would suggest you check and confirm the casting number on your 216 head to be "838773" as that is the head designed for use with your new domed pistons.
