Conrad,
Originality is preferred for unaltered guns, but once you cut the barrel, change the stock and do everything you've done then all bets are off. A collector is no longer interested in the gun and the value is in it being a cool looking, fun shooter. I'm impressed with the Dura-Coat, it is really tough stuff. I used one of the disposable kits with its own sprayer. If I did it again I'd just buy the paint and use my old airbrush. I would have had less problems with sags and splatters, the disposable sprayer doesn't give an even coat without a lot of work and a couple quick clean-ups and reshoots before it dried. But, the finish on this gun was heavy patina with some bad rub marks, now its uniform and great for a trunk/HD gun. I'm not going to go with sling mounts, thought about it but I like the clean look.