Take your chance with 743. THAI substitute this with new 744 frequently. When that happen, you'll be very happy to enjoy the new Royal First Class. And if you happen to get stuck on 743, the seat is bearable for this short flight. Enjoy the food and service.

Gulf Air is also offering F class on this route (old style, non-flat seating on A340) at giveaway price. There is a buy 1 get 1 free promo going on and the price per ticket comes out at around 15,000 baht. The lounge and overall service is inferior to THAI but the price can't be better!

Edited to say: Just re-read the OP and realize that he's on *A award ticket so the Gulf Air info will not apply to him. Anyway I left the info there since it's a good deal.