What are you asking? if you should bluff or not on the river read-less? and if you are asking this then IMHO you have no business sitting in a game that big.
As for the answer if he is good as you say hes going to know for sure a large part of your range is flush draws here, so hes going to snap you of quick as you like even more as it is the start of the match.
even if hes wrong he gains info on your sizing, timing, and all manner of tendency s.
..and I've also definitely seen reversed positions for live HU.
meh seems wayyy more likely to me that OP simply mispoke when he said "check TO him" instead of "check back" rather than two "good HU online regs" sitting there playing reverse button HU when they could just tell the dealer to switch it.
nice spot to shove, think his range is weighted heavily towards qx a lot of the time which is the best chance u have of winning the hand giving him bad odds, obv if he calls u can overbet shove lighter for value later on in the match, nice to make villains life difficult, u cant always check fold here like a nit in hsnl