Congrats on your new purchase! I bet it is a nice looking ride.
Yes, they are out there. If you're talking about the A/C compressor, most any auto parts store can get you an R6 compressor with clutch for under $150.
The important thing is are all the OE brackets there? These can be a bear to find, especially for a 6-cylinder.
Belts and hoses can be replaced. Hoses can be recrimped with new hose an the OE ends. I would change them just to bring them up to date.
The POA valve may be stuck, can still be purchased, and if the system is/has been open, then the dryer, still be purchased, will need changing. Expansion valves can still be bought over the counter fairly reasonable.
Freon R12 is pretty expensive, $90 per lb here. You might find alot of good products and info at www.oldairproducts.com
They have conversion kits to R-134A. But then, with the 1/2 quick release service ports, it won't look OE. The norm has been: If your going to change the compressor, changeover to R-134A.
Now, if you're looking for date coded parts, ie, hoses, belts, and compressor, you've doubled the price, if not tripled it. If you're not going to use it, close up the system and fill it with nitrogen. Its dry and will keep the moisture out of what is existing.
Finding a good reputable/knowledgeable A/C mech is a hit or miss. Ask around.You want one who will leak check using nitrogen at 175-180 PSI rather than using freon, this will keep the cost considerably.