That was my fear, the unused AC compressor locking up on a road trip, and the only way to continue on with a single fnctioning alternator, would be to get a different compressor or install an alternator or some type of idler pulley.
I had purchased a new 50/120 Nippondenso alternator which was a drop in replacement, when my chrysler reman'd alternator quit working while on the other side of the country.
i was told the ND alternator with its dual internal fans would perform better than the Chrysler. It is a ND clone, made in Malysia and must be short on copper in the Stator as it maxes out at 109 amps, and hot idle speed amperage comes far short of the 50 it claims to be able to provide. It does pretty good from ~750 to 1800 engine rpm though with a higher output curve, than the Chrysler
I found the chrysler 50/120 which was able to meet those specs and slightly exceed them, well the rebuilders screwed up the new slip rings installation, and the bottom brush was contacting both slip rings. I rectified this and while there, tried to reduce electrical resistance, and increase thermal transfer from rectifier plates to the body, and returned it to service, and the ND sat on a shelf for 10+ months.
It performs well and seems to be slightly better at hot idle speeds than previously.
When installing the ND alternator in place of the AC compressor, and aligning it, I found the original alternator location to be no less than 6mm out of parallel misalignment!!
I wound up shaving off 6mm from the ears of the Chrysler alternator, as moving the brackets inward would have been too much a PITA. I have gotten the alignment nearly perfect, but have not yet wired up the ND alternator in its new location.
One interesting note is the ND alternator has a larger gap between the pulleys than either the crank or the chrysler alternator.
My Alternator having been 6mm out of alignment for upto 230K miles shows the V Belts are pretty easy going on the misalignment front.
I often ask for the alternator's max output, and have been using only one V belt, as the dang AC compressor was angularly misaligned, and even if I were to be able to acquire matched V belts, one would be the right tension and the other too loose, or tight, and vibrate and cause weird annoying harmonics. So I just ran one V belt and accepted it would squeal when damp and needing more than 90 amps production.
My ND alternator has been nothing but an Idler pulley for 5500 miles now, but soon It will work for a living as I am nearly tripling my battery capacity.
Here is a good read, worthy of a bookmark and a regular rescanning, regarding the mounting and belting and aligning of Alternators.https://marinehowto.com/marine-alternator-installation-tips-tricks/
The Marine guys take it to the next level, as a failure of components in blue water passages could be life or death. It's good to see how far it can be taken, and then draw one's own line in the sand.
The good news is that installing the ND alternator in place of the ac compressor, was pretty simple as the bracket for the bottom of the AC compressor was the same offset, so one just worries about the other alignment points.
Back in '05 or so, I tried to better align the AC compressor and failed miserably, so am glad that is now no longer an issue.
While not an issue with a '77, when chrysler started putting voltage regulators inside the engine computer, a failed VR in the engine computer often meant a reman'd engine computer.
There is a way to trick the engine computer into thinking it is still coneected to teh alternator and thus not illuminate the check engine light. basically a 10 ohm 50+ watt resistor on the original field wires that attached to the back of the alternator
I run an external adjustable voltage regulator( transpo 540HD), and modified it with an external adjustment knob located on my dash, nect to digital voltmeters and ammeters, So i command the voltage the alternator is told to achieve/ maintain, and this can properly and quickly charge my batteries to at least 80%.
80% to 100% always takes no less than 3.5 hours even holding the battery at ideal voltages, but its nice to be able to get to 80% in less than a half hour.
The alternator at idle should be able to power many lower wattage window shaker AC without draining the battery, but I doubt the BTUS most window shakers are capable of can compare to a belt driven compressor.
window shakers are pretty ugly too, but if needed, and one can park and plug in, then good to have.