[kitcarbp]

Ok so for the 429 BB Ford bell housings, my Tremec TKO ( and the TKX) input shaft bearing retainer OD looks to be 4.8500 nominal. I’ve seen the same size quoted for the big block Top loader input shaft trans so it makes sense.
Back during my build when I realized I needed a choke ring I didn’t think I could find one so I drew one up and was ready to have a buddy CNC it, but common sense prevailed, and I called McLeod , they said yup , we have the one you need!

Here is the pic with caliper on it measuring 4.8480. blykins is exactly right, it’s a small interference fit nice and snug. I custom made washers used beneath the 4 mounting bolts to hold the choke ring in place. I could have glued it in with lock-tite but didn’t. My setup has a McLeod bolt on HTOB and thus I removed the Tremec bearing retainer which was handy for answering your question