Thats basically the whole question. I guess I'll do some light filing if I have to, but what gasket lines up the best to this manifold, maybe needing no modifications at all? I'm using 415 casting heads by the way. Thanks

Just tell the part store what yr car you have and that you want a fel-pro, that should be all they need to know.

Mine fit with no problems.

I dont think telling my parts store what year the car is will help my situation. It never does. I tell them I want an oil filter and they ask me what year is the car and engine size, they put it in the computer and then look at me with a blank stare and say "NO, you don't have a 350 in that car, the biggest engine you can have is a 305", I tell them I put the 350 in myself and then they say "well we can't look it up in that case". I have resorted to looking things up and getting part numbers on my own for this reason.
My heads are 415's that were used on 1980-85 267/305's, and the block is a 95ish "hecho en mexico" Goodwrench block. If no one knows what I need offhand, should I just tell the parts store idiot that I have a 1983 4.3L caprice? I was hoping I could get a part number and order it from scummit.

Felpro 93317 lineup nicely with my street dominator check them out That is the part number on my gasket
right here in front of me