A while ago I purchased the Revell Motorsports version for the Reher & Morrison Pro Stock Camaro. I think what you ran into is what Revell did with this kit as it’s unbuildable as is. The body is the original 1984 released body with correct Crome tree and the newer version Summit Firebird Pro Stock chassis. I,ve included pics of original and the newer kit chassis. The chassis pans are completely different, and if you look closely at the body pic, the wheel base is close, but too narrow for the early Firebird/ Camaro bodies, the roof on the newer Firebird is substantially lower. This would create all kinds of fit issues.