Windage Tray and Main Bearing Cap Fasteners

I don't have a history of this engine running so I'm unsure of the running condition of the factory fasteners. If I'm going to throw $3k+ in my short block, I would like to have fresh fasteners that are not fatigued.
It sounds like studs are the way to go with a 12 point nut under the oil pump- does anyone know the PN for that nut?

I don’t mix bolts and studs.

I machine the cap so the stud doesn’t hit the pump and I use a shorter stud there.

If the machine shop you use doesn’t understand how to do that get a new one.