Set the timing one or two degrees more then the book says and leave it, you are creating more then one problem at a time. Its not going to effect it much from one end of the scale to the other.
First order of business is to get fuel flow and volume. Low pressure can really mess you. I finished up a hotrod Pontiac last month that wouldn't run quite right. Idled OK and run around town with out much problem, but was low on power much like yours. Turned out the fuel regulator had backed off to 1.5 psi. I set it back up to 4.5 and the thing came alive. You could even here to difference in idle.
I would bet if you shut your engine off half way up the hill when its cutting out, you would find the carb half full or less of fuel. Add a pressure gauge where you can see it and monitor the fuel pressure at the carb inlet. You could also add a short piece of clear tubbing in the fuel line where you can see it and go for a drive, I would bet not much fuel is flowing when needed.
Joe
Joe