I just did a set of originals and they turned out nice. They had some moderate denting and rust holes. It took a while to restore them. I did the outside and inside both. I think you probably know to use a long board to sand the filler flat after you have used a body hammer and dolly to get the dents pretty well worked out. I think you should be able to restore the originals unless they were really beat up badly. There is a trick I learned from someone that does very good bodywork. Get some ABS plastic (1/8" thick) and cut a piece about the size of a paint stirring stick. Wrap sandpaper around it to do your sanding on curved and tight surfaces. It really works well as the ABS plastic bends a lot without breaking and follows the curve of the panel well.
As far as repros, DON'T buy the cheaper ones unless you don't care if they look like the originals. They don't have the indentations on the front and rear near where the fenders bolt on. I bought a set, not knowing that they were made cheaply and didn't look right. I still have them as I don't want to use them. I am pretty sure they were made by Howell's in Texas. Howell's doesn't make very good repro parts as far as I am concerned. I believe Rootlieb makes authentic aprons, but they cost a lot more than the cheap ones from Howell's - around $280 to $300 I believe, compared to about $200 for the non authentic ones. Hope this helps.
Rusty Nelson
Lakevile, MN