I agree with Pat on this IF you wish to go with an aftermarket system.

From first hand experence the Chrysler systems from the late 60's were actually pretty good however. They do loose a lot of effency when they are converted to R134 however. I have had good luck using the drop in R12 replacements and as long as they are available I don't see me doing anymore 134 conversions.

In the case of a Road Runner which have become relatively high dollar cars from strictly a value standpoint it would be best to stay with an OE system. These should be readly available and not all that pricey if you can find an appropriate donner car. Any of the 69 (and 68) Satelites to include wagons with factory air should prove a good doner.