Thanks guy for all the help and suggestions guys, much appreciated!
So far, I've decided on:
Oxycheq 30LB wing
Aluminum backplate
DIY HOG harness + crotch strap (20' webbing, 8 Tri-glides, 3 alum bent D-Rings,
Trim pockets
Plastic Cam buckle (from old system i got used)
SPG and Depth Gauge (from old system I got used)
MAYBE the Atomic reg for the swivel hose or a the Mikron reg.
This old system i got seems pretty old, from the 80s. Its a Dacor 950 XL reg. The tank still has air but it is a bad Luxfer one. Should I be worried about the Inflation hose and SPG hose? What about the cam buckle? It was pretty dusty and seemed to have sat outside so that is my concern. I have not inspected the hose closely and try airing it up yet as it needs to be cleaned first, but I figure for $25 I made out on the depth and pressure gauge, and a tank to just 'feel' out the system as I build it, and then use it as a novelty piece.