50% because I don't know a thing about wiring.
25% because I am confident I can do the plumbing for a valve (I have some plumbing experience and I'm going to make my new fuel lines anyway so now is the time).
25% because I like to layer my defenses.
Bonus: I want to put in an extra fuel filter under the passenger side of the cab and a fuel valve would keep me from dumping gasoline all over my garage floor when changing that.