Grant,
Another completely different approach is to pull the hot water from the block like I did in my 1995? There should be a removable plug in the block similar to the water temp but on the other side. Just put a brass feed line in that instead?
You could also try the poly fittings from these guys, they should hold up better than the PVC to the heat:
http://stores.ebay.com/TANKS-MORE they have almost everything