Picked up a parts car FB wagon today(actually the body isn't that bad!), but anyway the engine number was 129*** would that make it an early FJ block do you think?
Yep, you guessed right Peter, its an early FJ engine ( providing there's no prefix letter before the number).
FJ's started with engine number 121694. Later FJ's had the letter "U" prefix starting at number U 283384.