It is just like Ed said, the numbers don't match up and it shows that Bowers is using different math than the rest of us. You can't have 11:1 compression with the flat tops (-3cc to -6cc for valve reliefs), 124cc chamber, 11.5cc for head gaskets, not even to count the 1 to 2 cc's for the top ring to top of the block. You are closer to 10:1 compression because the total combustion chamber volume is from 140cc's to 145cc's.
The sweep volume ( V ) is the volume of one cylinder in cc’s, which is 1293.8cc’s. The total combustion chamber volume ( C ) is calculated as the head combustion chamber plus the head gasket volume minus the dome volume of the piston (yours will be add the valve relief volume), plus the volume due to deck height and ring land. So, that is roughly a total combustion chamber volume of 140cc’s or 145cc's. The compression is calculated as ( V + C ) / C
(1294+140) / 140 = 10.25 : 1
or
(1294+145)/ 145 = 9.92: 1
I had another shop tell me that they could get the big compression with the flat tops. You can but the head chamber needs to be smaller.
Good luck on the rest of the combination of the engine and the Willys sounds cool.
Bill M