P-38 engines left/righ

[Staga]

Thing is that Griffons were built that way and not modified afterwards.

For example DeHavilland Hornet did had counter rotating propellers but its engines  were ordinary RR Merlins and the change in rotation was done in reduction gears.

[Charge]

I have never heard of anyone putting two head gaskets on another to decrease compression. Not to mention in supercharged engines.

In automobile conversion kits from normally aspirated to supercharged there is just a thicker head gasket, not two of them. (Maybe in very low compressions but not on those close or over to 1.0 pressures.)

To decrease compression it is also adequate to use different  pistons (the case in DB?).  Or maybe the DB too had asymmetrically placed crankshaft and with connecting rods of equal length this naturally produces a slightly lower compression to other cylinder bank. Was this CR mod made to counter torsional vibrations in crankshaft?

BTW It is not advisable to machine the whole top lower as the piston rings may get stuck eventually but to machine a lower area to 4/5 part on the piston top provided that the top thickness remains thick enough.

-C+