My '52 GMC 228 came to me 12 years ago already converted to a 12v negative ground system. The coil was marked "12v" and had an internal "ballast" resistor that could not be bypassed like a slightly more modern (say 1956 and newer) system with an ignition switch with a start position (or a stomp starter switch with a bypass terminal), 12 volt coil, points and condenser can be when starting. I think the C15 or UC15 in your post would be such a coil. Some (me included) would argue that using such a coil would cause starting to be harder because the lack of an external bypass for the ballast resistor and the coil having a non-bypassable ballast resistor. Mine seemed to do okay.
That said, I've been using a Deve designed HEI system for years now with no complaints and very quick starting under both hot and cold conditions.
As for a condenser, contact forum member Jon G.
'57 GMC 102, Original 347 V8, HydraMatic, 3.08 rear gear, added A/C, disk front brakes, HEI, AFB carb, '98 Honda Black Currant paint. T-boned and totaled 10/12
'52 GMC 152 Stake Bed, Original 228, SM420, added A/C, HEI, disk front brakes, '67 Chev 3.55 rear gear. Gets used as a real truck.
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