The main-girdle bolts are torque to yield, even depicted in the Ford shop manual that way.
I rebuilt a 3.0 last winter, a set of ARP studs was cheaper than buying new/NOS Ford bolts - which would have to be sourced onesy-twosey around the country.
Nautilus Performance Group sells the ARP studs for these around the $320 mark
The connecting rod bolts are torque to yield too but they are the same as Ford's 90s-00s modular V8, pretty much the only way you'll find any is in a set of 8 pairs for the 4.6 V8.
I have my doubts about the main bolts actually stretching but the rod bolts definitely do, being we got enough bolts for a V8 I "wasted" a pair of new rod bolts to measure the stretch after torqueing and they stretched about 1/16"