wonder what can be adapted

If it was me... Knowing that my system is completely empty.... Id pop a can a dye and a can and a half of freon in it. Use the funny light and glasses and see where its leaking from. When you remove the hoses go backwards (towards the bed) so if there is any freon or dye in the hose is doesn't spray on your compressor. (It will appear your compressor is bad) if dye is not leaking from the front of the compressor its probably fine. Foreign cars are pretty good about the compressors. They usually leak from the seals. I wouldn't spend money that you don't have to.

if you want to check your compressor just hook up some jumper wires and touch it to your battery, or even a nine volt battery to see if the magnet in the clutch cathes. dont do it while its running though cuz it may burn it from running with no oil. thats how i would check compressors in the jy for ones that were going to be converted to air compressors.