Is the Alpine rad. made out of alum. or copper?
If so, why couldn't a "good" shop just remove the tanks, boil them out and replace the core, then pressure test the assembly?
There are some shops here in SoCal that I am sure could handle this but you should have the same in NorCal.
It should only take a few days to do this. Even a complete custom job only takes 7-10 business days. Just ask any top fuel/funny car racer.
I'll root around and see what I can find out.
Can you post some pics of the front, back, top, bottom and sides with approx. dimensions? It could help.
1998 Gulfstream 36' Sun Voyager Bus Platinum