Transmission ID and lockup/non lockup verification needed

Pilot size(snout) sizes:

To 1967: 1.550"
1968 on: 1.810"

And NO, you cannot machine down the larger pilot to the smaller size. There's not enough metal to do that. It's not a solid piece. If you've got the early engine, you've got two choices: 1 get a custom converter built to fit the pilot hole in the crank or
2 pull the crank and take it to a qualified machine shop and have it bored out.

Choice number one would be the best option. It's not a big deal for any qualified converter shop. What they do is use the front(engine side) half of the early converter and weld it to the later other half. No big deal, the shop that I worked for in the past did this on a regular basis.