Off the top of my head
Belt Tensioner
Shifter cable
Exhaust hanger
radiator
AC lines
Seat foam for front seats that isn't monte carlo that I had to modify
Rear seat foam.
There is someone that makes the exhaust hanger on tb.com that does it right (the exhaust hanger that comes off the transmission bracket). I'll see if I can find that information again.
There are lots of drop in radiators that work perfect. Unless you're really wanting a stock appearing one...then that is different.
Shifter cables or those little white plastic/teflon shifter pieces that go in the shifter assembly? I think have a NOS shifter cable somewhere but I didn't think they were becoming another unicorn piece.
Everything else you and other folks mentioned I would agree with.
I would add rearview mirrors with the original hard plastic mount and not soft one that warps in sunlight and falls off.
Tail lights...thoug
h that might make the 4 complete NIB NOS sets I have suddenly drop in value significantly. I was going to put my kids through college with those