It seems that the 73 to 79 cars will be some work or old OOP kits need to be found. The MPC Spoiler 'Vette will work for the 80 to 82 cars (with a cross fire injection unit needed for the 82) and it seems to be easy to find. I remember a good 78 pace car kit years ago which will also do a 79, but it may have been 1/24.
The 70 to 72 cars would be easy from the AMT 70 kit, as the only external differances were the color of the park lamp lens, clear on 70, amber on 71 and 72) exposed screw heads retaining the grilles on the 72, and a thief alarm switch on the rear of the 72 (looks like a trunk lock cylinder)
The 73 cars sat higher (federial standards on bumper heights), and had a new rubber front bumper without the rubber gards that came in for 75, a longer hood that eliminated the wiper door at the base of the windshield that was used from 68 to 72. also was a new open side scoop in the side fenders that replaced the 70 to 72 "eggcrates". These open scoops ran through 79.
The 74 cars would need the same work as the 73 but also got a one year only rubber rear bumper with a seam in the middle and no black rubber gards like added to the 75's. Also the rear quarter panels drop lower behind the wheels to match the bumper, you can still see the body line where the old quarters bottoms were. these new 74 rear quarter panels ran through to 82. With the new rear bumper the thief alarm switch moved to the left front fender near the Stingray nameplate. 74's have no crossed flag emblem on the gas cap.
The 75 and 76 cars got a new front bumper with black rubber gards, and a rased center that starts up between the front headlights a few inches. the rear bumper lost the seam and gained the rear black gards too.
77 lost the Stingray nameplates, gained crossed flags in their place, and the A post trim is now black. The Corvette block letters on the rear bumper are replaced with a one piece emblem, and the crossed flag emblems are a new style. Inside there were big changes to the dash and console. Also a new leather wraped steering wheel if T&T wheel equiped.
Sometime around 76 or 77 the hood lost the cowl grill near the windshield.