G'day Nick,
I have the same project waiting in the winds for me to attack as a 9SQN Vietnam Helo using the Dragon kit with a few stolen parts from the Academy C model I'll describe each mod as best as I can and if there are any particular reference pics you are chasing E-mail me and I'll check if i have what your after in my Iroquois stash.
To do a late model Bushranger will be reasonably straight forward they did indeed have forward firing miniguns on the forward hard points (just behind the pilots doors) and 7 Shot exposed type rocket pods on the Aft hard points (roughly in line with rear of cabin door).
The ammo bins resemble 2 square boxes with a pyramid type structure on top from the centre each has a belt feeding to the gun through a small cut out in the Quarter door(most of not all Late H models seem to have the window skinned over).The ammo boxes were fitted just behind the captains and co-pilots seats.
The quarter doors will need the wind deflector(thin sheet of metal with small holes drilled) added along the rear of the quarter door and the door guns disappeared from gunships a few years ago so for the pre retirement config leave them off.
When the RAAF/early ARMY flew as Gunships the sideways gunners seats were the only cabin seats fitted, the 5 seater and posts were removed but later in the piece they seemed to leave all the cabin seats in so you're probably safe to go that way.
The later UH-1H all seemed to have the IR suppression kits fitted (bowl exhaust, plates to the side if the doghouse, plate underneath) also the Tropical filter was added to the dog house.
The late aircraft did away with the Zig Zag antennae up boths sides of the tail boom and had a straighter antennae down the lower port side of the boom.
The Cabin has 2 handles hanging down from the roof resembling a towel rail on the port side and kind of a triangular shape on the Starboard to allow clearance when the hoist was fitted to Slicks.
Best check references for Aerial Config, Cable cutters are standard fit as is the framing sitting just proud of the top of the windscreen which is also part of the wirestrike mod the upper cable cutter also has a GPS antenna mounted to it.
There is a fold down gunsight from the top of the windscreen on both sides of the cockpit and a weapons control panel on the centre console (but this is getting super picky!)
That pretty much covers the visible mods/config issues i don't think i missed anything big Hopefully that can help you out. As for sourcing the required bits and pieces if you can get your hands on the weapons sprues from the Academy UH-1C FROG/HOG your half way there. the correct rocket pods are included as are miniguns with correct mounts and flexible belts. The pylons included are pretty close to what you'll need however the Acad kit only includes 2 you will need 4. it also includes a gunsight which will be useful however these will not be too hard to scratch I was lucky enough to know someone working on the same kit as a slick so was allowed to raid his kit for the parts i needed to double up on. The rest of the smaller mods will be pretty straight forward to scratch as for markings Hawkeye Decals should sort you out.
I hope this all helps if you need any clarification don't hesitate to ask good luck with your Bushranger
Cheers Cairnsy