The block deck height is 10.170". That's the measurement from the centerline of the main bearing bore to the block deck where the heads bolt on.
Bored 0.030", the cylinders will measure 4.082".
390 crank stroke is 3.784", so crank radius is 1.892".
Piston deck height (piston crown to block deck with the piston at TDC) is 0.010" and displaces 2.1 cc's
390 rod length is 6.490".
Combustion chambers are 74 cc's.
390 piston compression height is 1.778".
Crank radius of 1.892", plus rod length of 6.490", plus piston compression height of 1.778" added together makes a parts stack of 10.160. When fitted to a block that has a block deck height of 10.170", the result is a piston deck height of 0.010".

Now, let's shoot the static compression ratio with the above parts.....
(.7854) x 4.082 x 4.082 x 3.784 x 16.387 = 811.5 cc's in the cylinder.
(.7854) x 4.082 x 4.082 x 0.010" x 16.387 = 2.1 cc's in the piston deck height.
74 cc's in the chambers.
Estimate 8 cc's in the piston crown eyebrows.
Estimate 9 cc's for the head gaskets.
811.5 + 2.1 + 74 + 8 + 9 = 904.6 cc's total.
Deduct the cylinder cc's from the total 904.6 less 811.5 = 93.1 cc's.
Divide 904.6 total cc's by 93.1 cc's and find 9.71:1 static compression ratio.
Should squeak by on premium pump gas.
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