Not expensive in a sense if parts are free.
And you do 100 % of the work yourself.
The early C3 Vettes sometimes had fiberglass issues.
They talk about on Digital Corvette on old posts.
Sometime around 1980-82 C3 Corvette model run they made the body panels from SMC Sheet Molded Composite Fiberglass.'
A huge improvement.
Like Drawman Marc has.
SMC used on all C4 Corvettes too.
Big Block Factory Corvettes are highly prized.
If you can sell the TT for 30,000-40,000 USA $,
You can own a real nice Low compression Big Block Corvette.