1970 L78 Nova?

[BLACKLS5]

Hello everyone. I drop in once in a while but this is my first post. I recently bought a 1970 Nova SS that was said to be a L34 4-speed car with the incorrect engine. Chevelles are what I follow and own so I did some research before looking at the car and was convinced that it was a real Big block car. The owner and I struck a deal and I brought the car home yesterday. My question is without documentaion and the original engine, is it possible to determine if it was an L78 or L34 car? The car has the numbers matching M-21 and CBT coded 12-bolt rear. It has a single fuel line and was built the first week of October 1969. The car is Cranberry Red with Black bucket seats. What looks to be the original tune-up label lists it as a 402-350 HP. Any tell-tale signs to look for? Thanks, Troy