Hi Steve. Which Huey are you after? The UH-1B or D/H?I built Italeri's 1/72 UH-1B Iroquois a while back, the finished build is here http://www.scale-models.co.uk/threads/joes-completed-uh-1b-huey-helicopter-gb-2013.18613/#post-161795
It was a great build, highly recommended. Tamiya also released this same kit under its 'Warbird' range, so if you are keen I suggest sourcing the Italeri kit as it is cheaper to buy.
As for 1/72 scale UH-1D/H Iroquois. I have the Italeri and Hasegawa kits. Both require modifications to make the -H model, but not much. The Hasegawa kit is old and chunky, I haven't built it yet but I can see the framing for the glazing is too thick and the overall detail is not the best. It also has a case of severe rivet rash.
The 1/72 UH-1D Italeri kit is modern and has had great reviews. It's downfall is the side-door glazing. The side-door rear windows are too long and the front ones too short. You should be able to remedy this with some thought, or buy replacement doors from a detail company if you wanted to. Or you can go full-Vietnam and leave the doors off altogether.
Overall the Italeri 1/72 Irqoquois are the best for both the -B and for the -D/H models.
I don't know anything about the 1/48 kits.