Hi Bsarts,
LMC sells roof panels for 60-66 chevy trucks. The roof lines are the same in all these years, the windshields and pillars are not. Doors/pillars/windshields are the same for 60-63 only and 64-66 are the same for their respective styles.

https://www.lmctruck.com/body-components/body-panels

See the link or path above for reference or just google it too.

Usually it's the inner panel that rots out near the rear view mirror location.

I did a couple of these trucks, they are fun to do and you'll like it when it's done. Key is like anything: money, time and space. I had a crap load of the parts you needed, but sold most of them.

Cheers.