If you need replacement gas for the R12, you can try R406a which is sold here: http://www.refrigerantsales.com/

they call it Auto Frost as well, they are the same product.

406 is an hcfc, it is a smaller molecule than R12. Its actually a combination of R22 r143 and a small amount of butane to mix the mineral oil for compatibility. I have used it successfully in cars that have limited lenght rubber hoses, like an Acura I did which worked beautifully and has not leaked. But on my e30 BMW it would not cool properly. I replaced the rubber hoses with barrier stop hoses. to keep it from leaking but it would not cool much at all, I finally figured out that the H block expansion valve is adjustable in resistance to the gas, I tighten the spring adjustment 1/4 turn tighter on the valve and and it cools great.

On a car as old as yours I would replace the rubber hoses with barrier stop hoses.

But, if you don't want to go to all that trouble, you can just buy R12 in 12 ounce cans at the same supply house, I think you can get it without a liscence through the mail from them, I have myself in the past. Its not cheap but way cheaper that $60 a pound charged by most AC shops. It should be doable for $120. Do a good vacuum check on it first, make sure its not leaking.