Piecing together an A/C system

Presumably you have brackets to mount the Sanden compressor. Easy for a V-8, not so for a slant-six, but there is a long post here for those options. I think a larger condenser is always good, even if bigger than the radiator opening and parallel-flow is 30% more efficient. An integral filter-drier simplifies plumbing and mounting. The dealer retrofit condenser in my 1965 Newport sits in front of the radiator opening, overlapping slightly, with rubber seals around it to ensure all air flows thru one-way. An add-on electric fan for the condenser helps when sitting long as stoplights. No need to match fittings at each end of the hose, they just need to fit the hose size. Standard today is O-ring fittings, #10 at suction and #8 at compressor outlet and condenser inlet, #6 at condenser outlet and filter (liquid lines). Use barrier-hose (Viton liner). I have the Master-Cool ferrule crimper, but can suffice using Oeticker stepless ear clamps which still looks factory, or even Breeze smooth screw clamps.

Thermo expansion-valves (Mopar and most today) are better than orifice tubes (GM?). I think you can still buy Mopar style copper expansion valves with AN flare fittings and a thin copper sense tube, though I would prefer O-ring fittings (available?). New cars use an expansion valve block w/ face O-ring, but finding matching fittings might be hard. Your existing climate box w/ AC evaporator should be fine. If you get inside the box, you could add a Ranco anti-ice switch (older GM, my 1985 M-B). It is wired to simply disable the compressor clutch when ice, but Mopar never thought needed. If you add a pressure switch at the filter (smart), get a binary type to disable the compressor if either too low or too high refrigerant pressure.

Re refrigerant, seems you have been reading the humorous horror stories about HC refrigerant being "explosive". Spread by AC techs who don't want people easily maintaining older systems and hobbyists who never took engineering courses in combustion (me, need oxygen). I use Duracool (Envirosafe, others). No reported fire in millions of cars using it for decades, other than an Aussie AC tech who fabricated a fire. A 6 oz can is laughably dangerous. Fear carrying a newspaper in the cabin more. Plus Germans (and Austrians?) have HC refrigerant in their home refrigerators (kool-case). Works even better than R-12. R-134A is being outlawed. Can't use R-1234yc, which costs $$$ anyway. PAO 68 is the best oil for any refrigerant.