I've found a really cheap bypass regulator like this one, and was wondering how it would work using it for regulating water going to the engine. It's made for gas/alcohol/diesel so I would assume water wouldn't hurt it. 10AN inlet and outlet with a 6AN bypass outlet...just a thought since I can get one for next to nothing.
http://static.summitracing.com/globa...ei-13114_w.jpg