In a major step backwards, I removed the main A/C hoses and cut the fittings from them. I am ordering new hose, which I will install the charging ports properly into first and then the other fittings in place. A locall A&P has offered to help me install the O-ring fittings properly; the simple barb and crimp ring fittings I can do myself with no problem. I also did some measurement and am ready to tackle some of the remaining wiring, ordering a couple of harnesses from Aerotronics.
As far as actual installation today, I ran the copper line from the installed filler to the oxygen bottle. The filler end is well-supported by a grommet as it penetrates the nearby bulkhead but I chose to put a strain-relief loop at the bottle end rather than trying to tie the line to structure. Then I ran the lines for the emergency oxygen switch (a pneumatic switch) on the panel. Don't panic, the electrical tape across the package tray is only temporary and will be replaced with padded tie-wraps to hold the lines in place.