Engine code in the VIN = Y. Was this one of the 1976 Electras that came with a 350 because of the strike? Buick gave you a $159 credit if you ordered an Electra with a 350. But all I can find for engine code Y (5th digit of the VIN) for model year 1976 is a Pontiac built 301 CI engine.
Interesting seeing this information...but when I bought the car, it had the good ole 455 "blue" block.