[bigpooch]

Given one holds precisely a KT987 pat flush, there are the
following number of combinations of hands that are pat (or
better; somebody could stand pat on quads):

straight flush: 32 (only 2 in spades now)
quads: 344 (8x43)
boat: 2124
higher flush: 2122
identical flush: 3
lower flush: 1763
straight: 5880

The OP's hand will win against a straight or better over
62% of the time.

Arguably, the OP's opponent won't bet a weak straight (with
the possible exception of a wheel as a bluff), but at these
limits it is difficult to guess the bettor's range. Since
the OP played his pat hand quite weakly, the bettor might
be able to put him on a hand weaker than an ace-high flush,
and thus could be betting a hand as weak as KQJT9. This is
easily a call, since there is also a small chance the bettor
doesn't even have a legitimate hand.