I don't doubt the strength, but I'd sure as hell question the ability to
end
up with the pilot bearing in the crank concentric with the main bearing in
the trans. One that is not is likely to be the cause of premature clutch

FWIW,

My son's mustang needed a different bell housing, and the only one we could
find in the salvage yard was severely cracked. I welded it up and then had
to re-machine clearance for the ring gear. Worried about just this problem,
I bolted the bellhousing to the engine, and then slid the tranny on where I
could feel the fit into the pilot bearing, I got lucky, it was perfect. My
"plan B" would have been to pin the tranny where it needed to be and redrill
and tap new hold down bolts. (This idea wouldn't work on GM products - the
bell housing and tranny are one piece)

The car ran with this real well, till he blew up his Crate engine. Right now
the engine is in pieces in the shop waiting for funds. ( Me thinks this is a
good thing - maybe the kid won't blow the next one so soon) In the mean
time, the kid drives my old minivan.

Karl