[Formulabruce]

"Align Bore" I get nervous when its mentioned as doing it "correctly" on a Pontiac is Not the same as a Cheby.
Often the rear cap and or block is NOT "finished" where the seal is and bam you have a leak.
Also, on ANY block that is "Aligned" Bored I would plasti-gauge the mains, And Rods. I have the correct tools to check, but across
the WHOLE width of the bearing surface is a biggie.
I believe your clearances were too tight when assembled.
A Hypereutectic piston would cause you MUCH less block wear, give you much longer longevity.
>> Hesster77 << above makes a EXCELLENT point about Forged pistons.
Your rods may be ok.. make SURE the assembly is balanced, not "they ship those pistons within half a gram" I have heard a bunch of times. ( BS)
I am Not a fan of scat rods, but if they are round and true at the big end, they are cheapest forged.
Your crank should be checked.
Oil pump needs to be blueprinted and do NOT need 80 psi pump, maybe higher volume, but not high pressure.
I have seen blocks Ruined doing an "Align bore" incorrectly.......Hows the front seal workin' in the timing cover with the crank up 5 thousandths in that hole?
Usually they leak too.
Good luck with your project, hope for an inexpensive fix......But on a bright note its all Learning..