Anyone know what size the starter bolts are?

[Matt300ZXT]

I'm going to do a compression test on my 1JZ on a stand and I don't have the starter bolts. Apparently, since there's no threading anywhere to be found in the starter area, I'm going to just get some simple bolts from the hardware store and a couple nuts but was curious if anyone knew the size of the bolt so I don't get one that's too thick to fit through the holes, or too small and doesn't hold it very tightly in place. I'm guessing m8 but not 100%.