firstable, thanks for your answers, guys!
I forgot to describe my number:
my weight is 175 pounds (I don't want to get big because I think I'm heavy enough for a runner)
and I lift:
352 lbs for Deadlift
225 lbs for squat ( but with a very dangerous technique for my back)
215 lbs for bench press
Muscle-ups shouldn't be a problem as they're mostly pull-up strength and practice, and I know there's a special population of endurance oriented athletes (Navy SEALs, Air Rescue all Spec Ops really) who do a lot of pull up work.
I didn't think about it, but that's exactly what I want to be. like a Navy Seal. tough, strong, and quick. But my priority right now is to improve my stamina, for my next marathon.
You probably have room for improvement on your base squat numbers without gaining weight (height and weight and some base numbers would be more helpful here), but at a certain point any strength gain is going to hurt your endurance.
concerning strength , I don't plan to become an olympic weightlifter. I would be glad to lift easily 265 pounds for my squat, 420 pounds for my Deadlift and 250 for my bench press.
thanks for the crossfit Endurance advice! I'll try their WOD after my marathon!
@Andew: I looked @ your like, especially the second one, and it seems very interesting! one part talks about improving all the components of running, like increasing the footstep length, the aerobic system and even strengthen the upperbody! I like it!