How much travel the front needs has absolutely ZERO to do with anything about the rear suspension, what type, or what size tire you have. It has to do with car setup, weight percentage, power and how much (if any) pitch rotation your car needs to hook.

I have seen leaf spring cars need 4" and I have seen leaf spring cars need 1".......same with ladder bars and 4-links.

Every time there is a Calvert post, it is immediately said that "Calvert says" you need 5"............maybe on a low hp something that needs a LOT of pitch rotation, but usually not on anything with power and a decent tire.

And if you car won't hook with ladder bars, big tires and 3" or so of front travel..........the front is NOT the problem

Monte