How does one swap an engine for a trans?
And, out of the thousands of metric bolts that have passed through my hands I have never seen one that had either a .5 shank or head, they always move in even full MM. sizes there. Meaning 12 then 13.........the THREAD pitch moves in less than a full MM.
If any of the bolts pass through a dial pin then likely different length there.......and sometimes at the starter too. Pull one bolt, measure it for a starting spec then fit it in the other holes without threading it in, simply to see how much it sticks out, if all are the same amount then buy more in the length you just specced. The spec is generally 7 threads at least to have proper depth and holding power. A couple more is even better. You'll need the correct property class too or like 10.5, the strength of the steel used in the bolt. 8.8 will probably work.