That sounds a little low - my static pressure ('80 model W123 running R 12) is usually in the 70's in cool weather and up into the 90's in hot weather. Sounds like your system is still basically holding pressure though - some small leakage through the front seal of the R4 compressor is normal. I'd get a can of R12 plus a 2 oz can of frigi-cool oil meant for R12 (check ebay or craigslist). Also you need a good set of manifold gauges - about $30 on ebay used. Also you'll need a can tap if you're getting coolant in the small cans (instead of a 30lb jug).

Since you still have fairly good presssure there should be no need to evacuate the system or replace the drier. If you get into doing that you'll need a lot more equipment and you're probably better off taking it to an ac shop rather than buying and maintaining your own recovery machine although an R12 recovery machincan be had for surprisingly little these days).

The main thing is to make sure your cluthch is engaging and your front auxilary fan is coming on. An easy way to jump these is to pull the connections off the drier and use 20amp blade style fuses as jumpers.