Sb 1000 (As7sQc6h)
Bb 260
BU 1000

Not much hand histories but both should be decent players.
BU open preflop to 10, both sb n bb call.

Flop 10s 8s 5d

BU c-bet pot to 30, I(sb) call, bb repot to 150, BU flat, I folded as I was chips locking n about to leave e table. But I was ready to shaft if BU has folded. I do not want to be getting it in with just naked nut flushdraw if either one of them have a higher straightdraw. I should have at least flat to see the turn if I wasnt chips locking. Now my question is what is the optimal play for me when BU(deepstack) bet pot on this flop? Should I have flat like I did? Or reraise him? What if I get 3-bet from him after my reraise? He could have set and/or higher straightdraw.

Turn Jd

Bb shaft all-in for 110, BU call. River 4h. (I would have hit my lower straight on hindsight)

Bb had Qh8h8c7d
BU had Kh10h4s8d

You've answered this yourself, you've got a bunch of clean cards and plenty of equity versus their ranges and should be continuing in the hand (and if you weren't ready to commit chips on a board like this w/ this hand, then you should've folded preflop).

I would most likely check raise the flop. It often wins us the pot right there, and we're not even in terrible shape against a range of top two, sets, and wrap w/ FD that opt to get the $ in right here. Some minor consideration of getting it HU, where our OESD stands to be much more valuable than multiway.

There is merit to flatting and X/r flop but as played you should call, your straight draw can be dominated (e.g. QJ9x) but having the nfd your equity is never going to be awful even 3ways

Btn bets 30. I would lean toward the call here. We don't really need to push the bb out if he wants to come along to the turn, and if we were to raise and get 3-bet by the btn it wouldn't be a super great spot. I'd only raise if I thought it had good fold equity.

When the bb raises though our fold is terrible. NFD and open ended getting 3:1 with money left behind...I'd do away with this concept of "chip locking" and just sit out instead.

Thanks guys for the responses. Really appreciate it!! : )