Posted for Finn Lassen <finnlassen@netzero.net>:

Unless you have another input to the engine, this is where the oil enters the engine! I beleive it runs straight up to the oil filter pad, but I'm not sure if it doesn't also branch off to somewhere else.
If it's a straight run (no branches) and Bruce has cut off the oil filter pad and machined a hole for a fitting for oil input to the engine up there, I see no reason to even block off this hole: even a wood dovel to keep out the mud daubers would do.

Finn