When i look at the original Behemoth the following things strike me.-
The legs are more funky in the original than the turret. They are too long.
Maybe if you kept the upper part of the turret and gave the legs a wider stance than in the original.
This way the legs could still be somewhat long but it would look steady and capable of handling even the harshest of recoils.
Take a look at the legs of a crab for example, but make them more capable of forward locomotion.
I would also suggest taking a look at a turtles legs and it's bonestructure.
I made a mech once that has a lot in common with the Behemoth exept for the legs and the fact that it had arms and two turrets.
Not certain i should post it here.. I called it the
Flat Crab. It looked like a cross between a crab and a roadkilled toad to me.
With a couple of turrets on top of course.
I could send it to you by PM if you wish. You might get a hint on how to arrange the legs.