If you have a local shop that does radiator repairs, alternator, ac compressor or starter rebuild shop near you they usually can perfom a stock rebuild or a higher end more powerful and more energy efficient upgrade.
I have used a shop here in Linden NJ to do some of my parts with great success. I will look them up and see if they are still there for you, as I have not been there in about 2-3 years. The guy was like 88 years old that owned the shop and it was him and one other guy that worked there. Their combined age was at least 160 years old. They did great work. They rebuilt a starter and an alternator (which is not an easy feat) for a 993 for me and did 2-3 radiators for me over the last few years (not porsche).
I will search and get back toyou.