Most of the time it's easy enough to fit a generic headlight switch from NAPA (ask to see the switch catalog!)to an older Rambler, especially up to 63 American and 62 big cars. After that
I never thought to try that. My solution was to disassemble the headlight switch, replace the burned-out contacts with homemade contacts from sheet brass and stainless screws, then install relays up front. This was around 1990, pre-internet and I didn't know of any AMC suppliers then. The relays take a fraction of the current that the headlights do so even a crap switch will last a long time. It's still in place today.
I took this to an extreme in my 70 Hornet. When I wired it (from scratch, spools of wire) I ran all the front lighting through one small fuse (part, head) and used relays. I used #18 wire, so the harness is smaller and easier to work with. Used #8 to supply the headlight relay set and #10 to the lights, about 24" away. Should have good solid battery at the halogen lamps (Hella).
ANd grounds -- having nothing but old (over 20 yrs old) cars most of my life I've gotten sick of farting around with bad wiring. For anything mission-critical (ignition, start, headlights, etc, pretty much anything but stereo) grounds are made by:
* clean wire stripped * crimped ring terminal * solder the crimped terminal * drill 1/8" hole in chassis * sand/file 1/4" diameter bare metal * sheetmetal or through-hole screw (#6, #8) terminal to chassis * soak with black enamel paint
Sounds extreme, but it works 100% right, 100% of the the time, and essentially forever.
For inline splices, under-hood I strip the wires, twist end-to-end, solder, with heatshrink over it. Soldering is reliable, crimped butt splices are not if there's moisture or heat around, and electrical tape is a joke under the hood. It's not even very good for stereo connections under the dash, though I admit even I will twist and tape speaker connections :-)