1) Removed cam and inspected all eight lifter boards. Removed pieces of case sealant found in the pushrod cups of two lifters. There is an interesting circular wear pattern on both lifters nearest the prop bearing. All the others show and evenly worn face. Since this pattern appears in both lifters and not just one, I suspect the issue is in the cam lobe and not the valve spring pressure in one particular cylinder. 2) Confirmed that the camshaft uses only one thrust bearing. Modern builds use two, giving the cam a full thrust face to bear against. There were no manufacturer markings found on the end of the cam or a size stamped on the cam gear. The back of the cam has "C21" or possibly "C27" stamped on it. Confirmed that all cam bearings are standard size by virtue of the "STD" stamped on the back of all the bearing shells. 3) Removed the flywheel case seal. The seal has three different markings: "70 x 90 x 10" , "Elring" , and "15". A piece of case sealant was found in the back of the seal. 4) The aftermarket Japanese J311 connecting rods have the tang on the upper side like the stock rods, so these will need to be reinstalled facing up when the time comes. 5) The crankshaft cross-drilling plugs were inspected. Normally these are removable cap screws to facilitate cleaning out the oil passages in the crankshaft. This one appears to have pressed in aluminum plugs.