If it's a numbers matching engine and trans it is definitely worth the effort to bring it back. There have been cars in worst condition fixed to where you couldn't tell it had been done.
My 73 Cuda will be lucky to have much more than the Dutchman panel, one door, LH rocker, and the trunk lid as original panels when I'm done. Everything from the firewall to the bumper on the bottom of the car is new metal, as well as the roof skin and quarters, due to getting T-boned and repaired incorrectly and rust.