AC on 1988 Help

When I purchased the car in Oct 2016 the ac did not work this is the last thing that right now is not working. My mechanic said it was original r12.  He tried to jump the pump but it did not go on. He is not an ac equipped shop. He said that air or could be refrigerant hissed out.  I was thinking about buying some r12 on Ebay and see if the system would absorb it.  Before I do that I have a 134a gauge would this fit the low side of my 1988 corvette to see if I have pressure when ac is on.  If any thing major is shot the cost would be prohibitive. It 's a convertible so I could live with no AC. I am nervous about R12.

Thanks for any suggestions!!

Al