Welcome on board navan. First off, a 67 327 motor would not ave had a large journal crank. If indeed it is a large journal crank I would say you probably have a 350 block.
If it was a high out put 68 327 it could have a large journal steel crank. "All 300hp and below 327 engines were produced with a cast iron crankshaft. All others were forged steel." According to Chevrolet by the numbers.
I agree with 68 Ragtop, a clean Camaro will still bring a respectable amount of money, but I am not sure you would recoup the extra money spent saying an expert to say it is an original SS car since it doesn't have the original motor. A COPO, Yenko, Big block SS, or Z you would garner enough money to justify the expert, IMO.
Do you know where the original block may be? This would be the way to get the "big bucks" .