You should have a really good reason not to bet the flop here, since it seems like you don't just start with betting the flop 100% of the time when you have the nut draw in a limped pot and go from there.

I would also bet the turn as played. You should be betting a lot of turns after your opp limps then checks the flop (esp when the obv draw gets there). Turning the nuts here is a great spot to balance those plays.

Ignoring all that stuff, he's calling two bets with almost any spade and your read plus the flop check doesn't make a bluff seem very likely so a turn bet makes sense from like all angles. He can't really make a better hand either, maybe something random like bottom two.

As played I might over bet the river, say 120, but doesn't matter much.