My father started rebuilding some cars, took him a lot of time and money.
I've searched all over for parts, bought from ebay and a auction site - did not expected to find such good prices.
At the auction site found some good wrecked cars with original parts.
If helpful, the OEM seat bottoms are swappable from side to side; just four lag screws each from underneath if I'm remembering correctly. I did this a long time ago because the driver's seat bottom was wearing, but the passenger's wasn't much.