I used a brass screen type filter (for the early model TH350) and the regular hygard cut with a couple quarts of Dex 3 so i can see it on the dipstick. The converter I ordered was a little sloppier and this seemed to tighten it up a couple hundred RPM.
I don't think this old GM stuff is picky...
I've got stainless Hooker street stock headers on mine. Can't say I'd recommend it but they can be made to work dimpling a tube on each side to clear the control arm and minor trimming at the firewall. If you've got tubular lower control arms it would be a piece of cake...
It's smaller than the BBC bolt which is 1/2-20. Probably wouldnt have to drill it out any.
I've just ran the tap in there on stripped exhaust manifold bolts when I couldn't get a drill into position.
I thought they would need to actually produce something to need a production manager.
Probably wanted it to sound like a legit company.
Guy that answered the phone spins his hat around the right way and becomes the "production manager" Lol