[badhabit]

I was wondering which sized screws you used? I have used M16 and M14 mostly for this but feel like they are too big.

I used M12 all over. The only exception being the threaded rods that goes all through the casting, these are M16 and are used for lifting/rigging. I've placed these M16s so they align with the center of gravity og the castings and/or where they makes good sense to have lifting points.