Main Studs??

69 Cuda 440 said

Mopar Big Block

Since this Block has extensive 'webbing', these Block Castings are extremely sturdy.

The Main Bearing bores have additional 'Lower and Mid' strength, and the sidewall
supports help prevent distortion.

It is a 'very rigid' Block {225 lbs. bare block}.

1/2" x 13 Main Bolts

We have never found any 'significant change' in the Main Bearing Size when using
Stock OEM Main Bolts, when using the 85 Foot/Pound Torque Specifications.

And, in applications where we used the slightly longer 426 Hemi Bolts @ 100 Foot/Pounds
of Torque, again there was no significant change.

Click to expand...

Going by that theory there would never be signs of movement or metal transfer between the caps and the block and that's not the case in most big blocks that get abused. I'll add that movement isn't failure either but to me that's a point of potential failure. Block rigidity and registers have little to do with it. It's the caps that distort.
Just out of curiosity - How far do things have to change before a change becomes "significant"? Are you measuring the bore, or the bearing installed in the bore?