Wondering if anyone can tell me what I need to do to drill a pilot bushing

Read my post #11 in this thread about drilling cast cranks.
383 440 swap. Same flywheel?

That's exactly what I was talking about in post 4 here.
I'm glad you weighed in so I can ask you.
Is seems like the way you finally figured it out would be that a rear main seal leak would be in front of the fly wheel and not affect the clutch face.
While a seepage from the pilot hole would be aft of the flywheel on it's face.
Is that the case?
I had already done mine to a later engine and I coated the inside of the hole with varnish.
As stated, I don't think the transmission input shaft touches the hole and I'm also hoping that later 70s cranks were not as porous as the ones you had to deal with. (76 is mine IIRC)
The register bearing will keep it where it is supposed to be?
Hoping.
And the thought occurs to me, that if all cast cranks are that porous, they all would be unusable with a 4 spreed car regardless of what is done in this respect.