I think with proper prep, the A scratch is safe at 600 hp, provided that it lives in an otherwise healthy environment. Do your diligence re cylinder wall thickness. Being out of balance or detonating might get a block blamed for another problem. Sometimes a cylinder splits because it is thin, and sometimes because it is mistreated. In my life, I have seen more cracks in 428 cranks. Hardly ever in the internally balanced ones. Same goes for mains. Many more cracked 428 blocks between the cam and crank bores, almost always #2 and #4. Bad register and cracks in the bolt holes………detonation and/or out of balance.
The ARP main studs for FEs are not good. You are better off with bolts. Older studs had a lot more thread engagement on the block end.
Free public service announcement…….if you stud an FE block, use the 351W stud, and bottom tap the holes in the block. The Windsor studs have more thread engagement. The holes in the block are not tapped to the bottom. You can stud five #5 FE mains with one set of Buick Nailhead studs. It is an easy spot face job to get the nuts slightly below the pain rail and use the Nailhead studs in #5. So four sets of Windsor studs and one set of Nailhead studs does five blocks with no leftovers. It generally does not hurt to leave bolts in #5 if you don’t want to deal with the spot face. Just align hone with it set up that way.
The deaper you can root the stud, the better. Hone the cylinders after that is done, and hone with the mains on it, and torqued. You will get better cylinders that way for a few reasons.
