Collector car values are a strong indicator of popularity, and perception of appearance is a strong part of of a cars popularity.
Value is only what someone is willing to pay for something.
Althoe I have severial (I'm old and have earned the right to gripe), Muscle Car is my big one. A Chevelle SS 396 or 454 is a Muscle car IF the factory built it, if you put a 454 in a Chevelle that left the factory with a 307 you have a Street Machine. Muscle cars were factory built, not home built.
I have tried the hardtop and uptop from the MPC '60 Corvette, and the hardtop from the MPC '57 flip front Corvette and all three will work fine, but the headliner detail in both hardtops will take some work. Downside is that neither hardtop have the quarter windows which must be there as they did not retract. Simple scratch build.
Is your "Bondo Glaze" an air dry product? (without a hardener?) If it is remove it completely and use a product that uses a hardener. I use Evercoat Metal Glaze.
I know a young man that was in your exact situation a few years back. He got HER house into great shape just in time for her new man to walk into a nice place with nothing needed. He had his maxed out Home Depo card to rub salt into that wound.
I'm another body and paint guy, I've been at it for 40 years now. It was a good profesion untill the insurance guys ruined it. Like the OP, I tried to play guitar for years before trying a Harmonica. I was a natural and did quite well with it. I still play open mic nights and set in with some local bands.
Monogram makes a "porportionly challenged" 53 Belair 2 door hardtop in 1/24 scale, and Revell makes a "sort of" 53/54 210 2 door sedan that has custom lights and a gasser style chassis that would be a real challenge to build anything close to stock from. The only resin body I know of is a Phantom 54 Nomad wagon.