Apparently my uncle didn't hold on to his dishcarge paperwork, DD214 now, not sure what it was in the 50s. Anyone have any insights that could lead me down the right path.

Service will be in the next week. How quickly can we get a flag? The headstone and other things I'm sure aren't as time critical.

Good luck. They were probably lost in the big NPRC fire of 1973.

Here's a good place to start:
https://www.va.gov/records/get-military-service-records/reconstruct-records/
https://postaltimes.com/postalnews/change-announced-for-the-postal-service-burial-flag-program/

Also, many/most funeral homes have extra casket flags specifically because they know paperwork can take more time than familes have. Talk to the funeral director about the VA paperwork issue. They may be able to provide a flag and then chase paperwork later.