Do you want to compete in Distinguished Revolver, or are you looking to hang in regular Precision Pistol?
I mention that because if you just want to shoot BE without getting into DR, you're free to use a red dot. Which I absolutely would.
Whereas DR requires not just iron sights but factory sights, a 4" or 6" barrel, and 158-grain semiwadcutter ammunition.
My personal choice for either would be the same--a 6" Model 14. You could have it drilled and tapped for a red dot if it isn't already. But if you didn't make me shoot a revolver, I wouldn't.