Blinds are 5-10-20 (straddle) and I picked up J8o in BB.
Its 6-w and flop was:

FLOP(120): J 8 5 ssd I check, old guy bets 50, everyone folds but me.. I call.
TURN (220): 6 h I checked, he bets 100, I reraised to 500 which is now practically his entire stack.

I put him to J[9-K] and !AJ, maybe he could have 55, but I think he has more hand like FD or OE+
hand like 6s7s or 9sTs, maybe some naked OE e.g. T9o.

Is our play here valid?

Thanks