interesting question... but a little paranoid to think they are on flush and an open-ended straight draw (i know you didn't say that specifically). i'd worry more about flush although i know straights are very sneaky.

flush and open-ended = 34 outs (minus a few as there are duplicate cards)....

flush and gun-shot = 26 outs (minus a few)...

if you bet and the two guys calls, you need 1/3 chance of winning and i'm pretty sure you have that....

is that correct??