360+engine stand= what bolts?

Here's what I do. I measure through the length of the mounting ears of the engine stand and buy bolts that are PURPOSELY too long. When you buy those bolts, also buy a package of 3/8 washers so that you can then space them out.

I also keep "on hand" a 3' length of 3/8 and other size threaded rods. In this case, 3/8 is fine, and buy a bunch of spare nuts.

Sometimes, it is advantageous to bolt through the two larger through - holes -- the ones which take the 7/16 bolts facing to the rear into the trans.

Make sure that you swivel the mounting head ears around in such a way that you do not create a "high leverage" situation on the block, IE don't use the topmost four holes in the bell pattern.