Production years for G and H 6 cly flatheads?

[frnkeore]

The M pistons are the same as the '49-'51 Lincoln.

3 ring TRW numbers are L908F, L846F, 4 ring L899F

Edit:
BTW, it would be interesting to sonic check a H block, to see how much "meat" is in the cylinder walls.

Since the V8 could be commonly bored .188 and sometimes .250. There might possibly be enough cylinder wall, to get .200 out of a H?