No that is Not how I would cut fuel... first it is a 24 volt valve, and you don't need a valve, use the one you have, follow the pull cable to the rack on the injector pump. You can mount a simple pull solenoid (around $25) that will do the same thing as the pull cable mount it at the injector pump where it Only pulls the fuel shut off (Not the cable).
Also shop around online you can find Murphy gauges for a Lot less... I would use Both a temp & a low oil pressure murphy gauge... run the solenoid current through a relay to keep from destroying the gauges and place a momentary pushbutton switch in your circuit to allow disabling the system during start up.
Yep, I linked to the 24 volt model, not the 12v. I'll scout around for the pull solenoid. That was actually my first thought, rather than the pricey fuel valve.
I have never been fond of the Murphy style gauges...am thinking about a simple 210 degree fan switch, and a low oil pressure switch, with a pushbutton switch to disable, and the pull solenoid. Like you said, about $100 in parts and a few hours of time.
For gauges, I am thinking about a set of aftermarket gauges with coolant temp/oil temp (for the hydraulic fluid)/oil pressure.
I just brought the tractor home this morning, I need to study the layout and figure out where these sensors/switches can be plugged into the engine. I want a nice clean layout.
John