The standard bolt that's used with the V-8's is a 7/16 X 20, with a heavy flat washer. That's the simplest option, and it uses readily-available OEM parts. I have rethreaded a few to 1/2", but it's not my first choice. The lathe idea is a good one, IF you've got a big enough lathe, and you do something to protect the front main bearing journal when you set up the steady rest on it. A piece of oil-soaked leather wrapped around the journal might be a good option.
Jerry
