Warranty paperwork for our old cars seems to be very rare, especially for serious engine work.
With my Silverado which is several years old now, I do have the full detailed paperwork of what they replaced under warranty when I bent a push rod and had a lifter go bad. They actually replaced quite a bit of stuff and there is a "kit" for this, so it must not be all that uncommon.
BUT, on old stuff, paperwork seems hard to find.
Well I came across something recently. A valve spring replacement for a 1968 Camaro L78 with 4.10 axle. I know this because I also have the POP. But attached is the warranty service order from late 1970. Remember, this car would have had a 5 year 50,000 mile warranty.
Anyway, I thought it was kinda cool.