For the hardline there are a couple of people, but Doc Nickel would probably take great joy in helping you out, tinkerer that he is. Just don't count on gettin it back anytime soon. I haven't logged onto his website in a while, but he has reorganized for better efficiency.
For the bolt pin, yes it was the cheap industrial looking thin with a loop on the end...I still have one or two in my junk box but you'll probably be better off cruising your hardware store. In Home Depot they're usually in the bin with all the little drawers, where all the specialty items are. Cruise more than one Home Depot, selection varies from store to store usually. I'd recommend replacing the loop/ring with one small enough that it won't get trapped between the backblock and the body. I ended up flattening the ring. For that really "sleeper" look you could use a rubber band/bailing wire/solder on the main body of the pin to prevent it from sliding over far enough for the ring to get trapped inbetween the backblock and the body as the backblock returns forward.
I also like the idea of the reg hidden inside a 3 or 4 oz bottle. I think if you used a short metal fitting (a tube that's threaded on both ends) and pass it straight through a hole in the side of the bottle (make the hole very snug fitting to heighten the illusion that the fitting is screwed into the bottle). The fitting is readily available at any hardware or autoparts store. Also, if you cut off the bottom carefully enough, you might be able to re-attach it so it's not that noticeable (a few stickers and a little polishing can go a long way) and I think that if you just drill an access hole in the bottom or the side of the bottle (whichever way you adjust your velocity) and then either use a piece of black plastic as a flap, or a sticker that's only attached on one side. That way you don't have to use a bottle cover.
If you take an old, stock bolt and bore out the inlet hole and possibly bevel the part facing the ball if it isn't already beveled it should actually work pretty well. Just don't nick the notch that the O-rings sit in.
Ray