[nkaminar]

I believe that the 5.5:1 or 6:1 heads from Snyders will provide about 110 psi compression. I could be wrong. One advantage is that they are cast iron and not aluminum so you will not have to worry about galvanic corrosion. I used the graphite head gasket recommended for the high compression head with the copper spray gasket cement. This worked the best for me of any of the various head gaskets.

The high compression by itself will not cause any problems in the bottom end if the bearings are in good shape. Cruising at part throttle does not add significantly more force on the rods and crank. Of course, an engine built for cruising will last longer.

There is more to head design than the compression ratio. The combustion chamber design is important as well as the clearance for the gas flow through the valves. In my opinion, the Snyders heads are a good design. I don't think there is too much difference between the performance of the 5.5:1 and 6:1 heads.