The two bolts on the bottom were put in that way to make adjusting the main bearing clearance on the #1 main bearing easier do do by changing shims. It could be done from the bottom by removing those two timing cover bolts without pulling the damper and fighting to access those bottom bolts. Since the 1955 second series engines came along that don't use main bearing shims, the direction of the bolts is a moot point- - - -there's virtually no reason to remove the timing cover between major overhauls that require pulling the engine, and the timing cover seal can be changed with the cover in place if necessary. Even that would be highly unlikely other than some sort of foreign object damaging the seal. Unless you put 5/16" heli-coils in the main bearing cap holes, it's necessary to use 3/8" bolts at the bottom of the cover- - - -definitely overkill!
Jerry
