I would nearly always lead this flop for fifty. I have the best hand an extremely high precentage of the time. Check folding this flop to this bet is folding the winner far more than is profitable. If you think check raising puts you in a bad spot if he calls, consider flat calling and leading a non spade for $100. Including jacks, nines and sixes.

This puts the same amount of money in the pot and it is very difficult to play against.