The really correct way to do it is to measure stretch by putting a dial indicator on the end of the stud as you tighten the nut. That's the most accurate way to measure the holding force of a fastener, measuring torque is a crude approximation.
WHAT DID THE MACHINIST TORQUE THEM TO WHEN THE BLOCK WAS HONED? WHAT LUBE DID HE USE? That's the torque spec, and the lube you use, or the hole won't be round. Use the same torque and lube the machinist used when he align-honed the bearing saddles after installing the main studs, use the same torque and lube the machinist used when he installed the torque-plate with those cylinder-head studs for cylinder honing. Anything else is going to have to be torqued-and-measured, maybe multiple times to figure out the "right" torque to keep the holes round, and that may not be the right torque to provide proper clamping stress on the fasteners. Keep in mind that the nut-end of the stud is probably fine thread. ARP installation torque AND LUBRICANT should be what the machinist used--but you'll want to confirm both torque and lube. If you have access to both ends of the fastener, you can do that. If you have access to only one end of the fastener, you won't know how much of the indicated length change is due to bolt/stud stretch, and how much is due to thread deformation, and how much is due to casting deformation. I guess in the aviation world, there are some fasteners that have been gun-drilled almost to the end. You drop a rod down the center, and you measure the stretch of the stud by how much the rod recedes into the stud with a dial indicator as the fastener is tightened. I've never seen this done, I don't know of any automotive applications that do this.
That all makes sense. There was an internationally known engineer and race engine builder named Joe Wolf whose shop was 2 blocks from the house I grew-up in. I'd go to his shop after school and watch him build engines. I recently read his history and his back ground was in aircraft engines during WWII. He had these long wrenches that had sockets on the end so he could have access to the end of the stud. He died in 1966 when I was 13. https://www.kustomrama.com/index.php?title=Joe_Wolf's_Hollywood_Speed_Shop
Schurkey.......you hit the nail on the head with your comment! "WHAT DID THE MACHINIST TORQUE THEM TO WHEN THE BLOCK WAS HONED? WHAT LUBE DID HE USE?" if you can't make the round bore hole repeat when assembly time, then you are pissing into the wind!
