----- blocks a direct visual inspection.

Having heard about leaking crank front oil seals, is the replacement
method a total engine case split or some kind of split ring seal similar
to old chevy small blocks?

There is a split seal for Continentals with flanged crankshafts which
installs without too much trouble.

A few years back I replaced a seal on a C-85 without doing enough
troubleshooting. After replacement, the leak remained. it turned out the
crankcase vent line had been moved and was pressurizing the crankcase.

Cheers:

Paul
N1431A
KPLU