Apparently it is. That casting number is listed as a 2 bolt main, 327 and 350, so a 3.48" stroke crank was made for that specific block. In 67 and older engines, the crank journals were smaller. Sometime in 1968, they made them bigger. Which is also to say that you could put a 67 350 crank in any 67 or earlier 327 block, just know that older ones are smaller and newer ones are bigger. You can go here
http://www.vehicleidentificationnumb...e_numbers.html to further research this. Good luck!
Craig