Chevy or ford.... If you have a ford just run it wide open. Chevy and olds should be regulated more for flow than temp.
http://www.cpperformance.com/c-502-fuel-valves.aspx

yeah, you can run your water up to a valve at the seat, but why would you want to do that with logs. Ideally you would do it to control the water going through over transoms (shut it off at idle) but with logs you just set it and forget it.

about the fuel valve, just get an electric one. the one linked by yourmom is a bit pricey and complex but gets the job done. I have a simple one that appears to be out of a car/rv and it works great. not sure what its from though.

Gate valve is figured out. I got water temp to be at 130-140 underway but at idle it will reach 170.. What's the ideal temp to run at?

Gonna check out Napa's product book for an electric fuel line selector when I go stock up on wix filters. I think my boat had one at one time cause there's an abandoned switch and looks like something was mounted on the transom where the fuel lines meet.

When I bought it the lines just T'd and the tanks drained simultaneously.. kind of. I didn't like the idea of one tank drying out and it not being able to draw from the other, so I put a manual selector on it.  It's not bad but a pita to crawl  into engine compartment to keep an even keel.

Good points guys