The only 1977 Vette kit was the MPC annual one that was issued in you guessed it... 1977! It was 1/25 scale, only the Monogram kits of this vintage were in 1/24. I believe that MPC also issued their corvette kits in 1/20 scale, but the 1/20 ones are not very popular nowadays. I picked up a built up 77 kit on ebay a couple of years ago for cheap, and used the body and hood only, all else was taken from the 1975 AMT convertible re-issue. As an owner of the actual car, you will notice that these vintage kits leave a lot to be desired when compared to the prototype, such as incorrect exhaust system and aircleaner, no power brake booster, no AC options on the belt or firewall, no emissions stuff and only an automatic transmission. Also the engine appears to be the same big block that came in the 1975 kit, too large to be a 350 which was the largest engine available in 1977. But the body looks nice and it even comes with the luggage rack on the rear deck that you mentioned.
The best source to find one of these is on ebay, but expect to pay at least $30-$40 for an unbuilt one. The 1976 AMT kit is a reissue of the MPC kit I believe, and most of the parts are identical, so this may be your best option as far as price and availability.
I am currently working on accurizing this kit, using the Revell/Monogram 1978 kit for reference. I'm trying to build a correct firewall and cast it in resin to get the correct brake booster, as well as adding a smog pump. Also the 1981-82 MPC kit has the correct exhaust with catalytic converter and correct air cleaner with hoses.
I also painted my kit Chevrolet engine red, which looks exactly like the orange one you have in the photo.
Hope this helps,
Dave Calhoun