Hey Art,
I have to ask.. do you really want to be shooting a 55# bow with those injuries? I am just thinking if you are having arm and back issues you might want something a bit lighter for just plunking to help get the muscles back into it.
I have severe arthritis, so I don't really build anything over 40# for myself or it just hurts to much.
With that being said.. I accidentally made a left handed 52" fiberglass re curve that comes in at around 30# at 28". If you think this might work well for you, I would be willing to finish it up real fast and send it your way!