headers for 87 olds cutlass

Battery cables, in my own experience, is like fuel line. Bigger the better.

Since your stuff isn't stock, you could probably go with 2ga minimum, IMO if you have a basically stock 455 with ~10:1 compression. If the battery is in the trunk, or ultra high compression like 13:1 or something you could go with 0 or 00. Electrical engineers could steer you better. It's like anything else, if you want to do it right, you need to add components (starter/battery/cable and wiring) that compliment each other.

The stock 307 OEM wire is about the same size as spark plug wires. 8:1 compression on a small bore engine and it should be a breeze for any electrical system in half-decent shape to spin easily.

I think American Racing may be the only place left that makes BB Olds Headers
https://americanracingheaders.com/c...g-block-1978-1988-headers?variant=29943922756

I used 1 AWG wire for my positive and neg. batt wires. Battery in stock location.

Hutch

I have American racing headers on my car, the fit and finish is second to none. They are pricey but 100% worth the money.

If youre capable of a little tube modifying a body bbo headers are a decent fit. My build on ROP https://www.tapatalk.com/groups/realoldspower/84-cutlass-lazzie-cam-j-head-455-12-0-s-t16755.html