Many moons ago I patched a couple of speaker holes someone had cut into the door of a 65 coupe. After smoothing my welds with filler and primer, I used 3M's gravel guard (green can I think) which dries hard enough to sand. A couple of medium coats, blended into the surrounding texture. After it dried, I sanded the tops off of the bumps, trying hard not to get it too smooth. Applied a sealer then painted.
While it wasn't perfect, it was acceptable and unless I pointed it out to someone they never noticed. BTW, I did practice a couple of times before doing it and would recommend the same.
That said, there are other options (nice used door shells) that are much easier. You'll pay out more up front but will have a better product in the end.
A little while back, my granddaughter was in the shop looking over my cars (hoping I'd promise to give her one, I guess) and slammed the door on one of my 64.5 convertible projects. There was something laying in the passenger seat that slid out when she opened the door. It put a large dent in the textured area of an otherwise perfect door. I guess I'll get to try out my PDR skills...
SamG