Are you sure your number is right? I find 3970010 for a 69 302 and it is a 4 bolt main block. There is also 3970010 for 69-80 350 that can be either a 2 or 4 bolt main and was used in pass. cars, truck, Vette, Camaro, Chevelle, and Nova. You will need the stamped assembly code number to determine exactly what you have IF the real casting number is as above. IF it is as you posted, I do not have a clue as to what it is since that number is not in my data base.
Trees