It is 9.480....stock. And it is also 40 years old. And most of the kits are for 9.500 blocks.
So the block is probably cut, and the pistons are probably tall, but the good news is it's easier to establish your block height.
Just figure how far out of the hole the piston is sticking, and subtract that from 9.500........
Have your machinist check it, you'll probably have to cut the pistons.