i've seen this situation a quite a few times and the results have never been pretty when i get it in (or the person i see do it gets it in)
with those blinds and antes, there is approximately 60k in the pot, plus your 50k and the sb flat of 50k, and then the bb shoves for 140 (raise of 90k), creating a pot of about 300k. you have about 350k behind, if im reading this right. shoving that, the 'super deep' sb only has to call another 350k to play for a pot of about 900k, so i doubt he's going to fold.
he was strong enough to flat from the sb to play oop when you'd likely have to play for stacks on the flop, so he isn't likely to be scared here if you shove
the bb shove is almost irrelevant because of its size relative to blinds and antes, as well as the pot. he has an M of just over 2, so he's desperate for chips, tilt or not. the super deep sb has little incentive to 'gamble' with marginal or weak hands here (meaning he likely called you with a solid hand)
i'd fold. also, for what it's worth, with 400k and ~ 60k in pot pre, your M is about 6.5 and you could consider open shoving in that spot if the table has been tight enough or you could just fold