Oh ho ho. I've suggest some very expensive mods here. If you don't do these mods, get a few spare engines, and give it death. Hemi 265's are tough. If you are just socialising, then a few spares and some great company is all you need.
At present, the block and crank won't like high revs because the wall thickness needs to be 180 thou at the thrust faces to get reliable piston seal. The Val engine is a short rod engine which is over square, but it is quite a shallow block with small main bearings and crank pins. There is a lot of side load with the rods.
You have no doubt seen the Red VG Pacer at Summer Nats with a 4" bore 265 which did something like 400 rear wheel hp, or Townsends gold VG 265 Turbo? The red one was something like 4.030, +30 350 Chev pistons, or 120 thou over. Suffered blow-by, but still just about cleaned up normally aspirated sixes.
The avenue you should look to is survival under detonation. If you can push in enough fuel and advance via intake and ignition, then the next step is to
a) overbore to 4.02", and then sleave the block back to 3.91" with some bullet proof steel liners.
b) use the ACL Chevy 5.7 (346) LS1 piston kit, with some 1.36 tall V8 pistons. Blow coin on the aftermarket aftermarket small journal Chev 6.2" rods. The rods won't ever let go.
c) Hardfill the block to half the depth of the cylinder walls.
The old Valiant will then take any punishment you can feed to it.
Block stability is the key with this engine, and I can't see way any EFI Val can't rev to 7000 rpm all day with this combo.
If you torch a piston, the liner will hold it together,and you'll have a cheapish, avalialbe spare piston. If you over advance or try nitrous oxide, a turbo, or nitro methane fuel blends later on, you have it covered.
