Look for some old Silver Eagle straps on eBay.
I rarely play standing up, unless on stage w other musicians, but totaly strap crazy. Probably have 50 old ones... what are getting harder to find.
All of the old vinyl straps reacted with Nitro finished as we've all witnessed, as well as guitars stand meltoffs behind the neck... but usually only in extreme cases, like the strap laid under the guitar inside a very hot case... and the metal buckles, which I do love, I'm sure they contributed to some of the relic look...
My personal favorites for any guitar, bass, is a 3" wide leather strap, turned rough side up if there's a rough side. This is comfy, leather breathes better and doesn't cause excessive sweating, and more importantly, the shiny side doesn't grab your clothing, as in dragging your shirt down, it slides around and lets you move the guitar around without pulling on your shirt, that's how I like it.
If you're scared of previous DNA in leather, just go for new. Me, I just consider it Mojo... I picked a killer wide vintage leather strap from a local tech years ago that had been sprayed by a cat in his house, lol... Washed it, dried, aired it out on the line a long time, you wouldn't know it from any other strap now, just buttery soft leather, worn in, just the thing to save your shoulder from a 9lb 10oz Les Paul Custom...
Edit, just measured my old leather straps, and they are 3 1/4" wide.