Jack,
I assume you are talking about 1/72 since you mentioned
Hasegawa and Italeri. Really there are no great 1/72 kits of the
UH-1H, but I like the lines of the Has kit better. The Italeri/AMT/Esci
kit has the engine cowling too wide and just doesn't look as accurate
in outline as the Has kit. However, the Has kit has a bad rotorhead and
I'd get the rotor from the italeri kit to replace it if I could.
I assume this is the bird you want to build:
http://farm3.static.flickr.com/2129/2543232959_6fe580988c_o.jpg
If so, I'd check HERE for a nice walkaround.
I'm going to assume that this is the bird you want to build. It has the Fastfin mod, 212 rotor, tail boom strakes, and high skids among other big mods. If it's got to be a 1/72 build, you can get the rotors from the Italeri UH-1N kit. Otherwise, I'd recommend using the italeri 1/48 UH-1D/H as a starting point. It already has a 212 rotor. The Fastfin will have to be made from the kit [parts or scratchbuilt. The high skids will also have to be made. the tailboom strakes shouldn't be too much of a problem. You can get most of the other parts you'd need in the Fireball Modelworks ASE update set in either 1/72 or 1/48. there will be bits you won't need for the civilian version but Joseph's stuff is some of the best around. Anyway, that's my 2 cents. if I have the wrong helo, please let us know.
Ray
PS: Check HERE halfway down on the left for info on the Fastfin and strakes.