Tony...
This may be a bit late for you, but you have hit on a subject I can fill you in on. I have worked on and flown OH-58s in the Army for the last 18+ years.
OH-58A, A+, and Cs are two bladed semi-rigid systems with two tail rotor blades. The Kiowa Warrior (OH-58D(I)) is the four bladed armed version that we fly now.
I was also stationed at Ft. Wainwright from 91 to 93. The Kiowas there were A models. In 93 they were modded to become A+s and were turned into the Guard. The 6th ID reverted back to the 172nd INF BDE and only kept UH-60s and Ch-47s.
I saw pictures in 1991 of the 4-9th Cav's Kiowas in Red and White paint schemes, with high rise skids, skis and miniguns from the unit's past. When I got there they had the traditional CARC job with OG Blades (main and TR). If you looked at the blades closely, you could see the stripes under the paint (paint was thicker).
If you are building an A model, it may or may not have a tail rotor driveshaft cover, and will definately not have infrared exhaust stacks. It will have the curved ones (versus the mushroom shaped ones with heat vanes). It will also have round front windows, versus the flat plate later found on the C models.
An A model was upgraded to become a A+ by upgrading the engine, tail rotor drive train, engine driveshaft to KFLEX, addition of IR stacks and main rotor hub upgrade from oil lube to grease lube.
An A+ was basically a C model after mods, except it still had the round windows, instead of flat plate.
This was important, because later when the CS was fielded, it was an A+ with the addition of an ATAS (stinger) system with PDU (pilots display unit) for aiming the thing.
Also, A and A+ birds in good shape, became feeder aircraft for modification to become OH-58Ds. They went through two programs. The original was the AHIP (army helicopter improvement program), unarmed, followed later by by the Kiowa Warrior program where they received the OH-58D(I) designation for 'improved'. Now the aircraft is being upgraded again to the OH-58D(R).
My aircraft have three data plates in the nose. Most of them are 1970 models, with an upgrade to D model around 1985. The I model upgrade followed in 90/91. They are now slated for the next upgrade.
Back to your original scheme. If you are doing a circa 1980 model, it will have high rise skids, skis, a minigun, no tail rotor driveshaft cover (they collected ice), and possibly a red and white paint scheme. The minigun leaves a hot grease stain from the barrels turning on the side of the bird.
Hope this helps. If any of you guys are thinking about doing a OH-58D, I can send you plenty of pictures.
Oh and Tony...whatever model you make your cousin, I am sure he will appreciate it with all his heart. All us Rotor Heads day dream back to clear weather VFR with the wind in our faces and our cares left on the ground...
John