603/606 bell housing bolt size?

[abosely]

I’ve tried looking everywhere I could think of, but so far not found it.
What is the bell housing bolt size for 606/603?

I don’t need actual bell housing bolts, just need few to mount engine to engine stand.

I guess one other question is would 4 bolts into the thicker/more supported bell housing holes be strong enough to hold engine?

Or should I make 4 brackets that take 3 or 4 bell housing bolts each and then bolt engine stand head to them?
Have one ton stand that has 4 arms to mount to engine.

Looking at bell housing end of block it looks like should have more than 4 small bell housing bolts to hold the engine.

Cheers, Allen