Looking at both helmets now I am afraid I would say either the Boba Fett Helmet (which as I said is bog standard) or look for another helmet, as the other Helmet is not saying Mando at all to me, in fact it is saying Rebel Stealth Commando - however everything else looks spot on.
If you are going to go with the Boba Fett Helmet, I presume you are going to match it to the color scheme of the rest of the character you have done, if so do Blue mainly with the green where the red is on it, I think it may give that distinctive look, the other thing I may do to change up that Boba Helmet is if you have one put a different style range finder on the helmet, something like the ROC Breaker gizmo he has on his head, then mod up the helmet with that piece, then it would take away from the instant recognizable Boba Helmet.
But seriously do not use the other Helmet as it either looks like a Diver, or here's an idea don't put a Helmet on him, as he has the Bandanna on his head and looks ok without the Helmet on.