Answer: Corvettes may very well be the most popular collector car on the planet, and therefore parts are abundant. A brand new high quality aftermarket “front clip” will cost less than $1500.00. Apparently, the shop that is doing your repair feels that the labor and materials to repair your original front end will exceed the cost of the new “front clip” plus the cost of the labor to install it. This is not inconceivable, and even if the damage is moderate, it is likely that they are correct.
Once installed and painted, the new “front clip” will be virtually indistinguishable from the original when viewed from the exterior. However, even a cursory inspection of the inside of the new “front clip” by someone knowledgeable about Corvettes will reveal the fact that it has been replaced because the construction of the new aftermarket part is different from the original.
I don’t think that I would worry too much about this on a 1975 Corvette as values of these cars don’t really warrant the extra time and expense of repairing the original part…unless perhaps it is a low mileage, documented, L-82, 4-speed convertible, in which case retaining the original body panels might make sense.