Bolt size?

On my small block bellhousing (4 speed); as I working on re-painting it, I noticed that the bottom starter bolt hole threads are all damaged.

I took a 7/16" bolt out of it, but it looks like it could have been a 3/8" bolt in there originally and got re-tapped to the next larger size.

Either way the threads are damaged and I'm debating on weather to helicoil it, or weld it and re-drill and tap the proper size, but what size?

I will eventually go with a mini-starter and I'm not sure if the 7/16" bolt will go through the starters mounting holes.

Any light on the situation, as usual will be greatly appreciated.
Author: admin