Whatever you decide ( I vote road with bars), you had better get it, get it fitted and get riding fast. You will need all the seat time you can to prepare. The swim will not be that bad, but sitting on a bike for more than 30 minutes without training is enough to turn anyone into a SAG rider. You might want to look into some comfort items as well, screw the weight you are wanting to finish!!!
Good luck!
Cheers!!