SBC numbers?

I am using this motor to move a project around, it runs good but if its a 4blt block I might need to take a little better care of it. I am having trouble narrowing down if its a 2 or 4 bolt block.
Heads are (F270) & 3927186 which should be 69-70 302or350. The back of the block is 3951509 which is 70-71 4 blt or 74-80 2 blt. It came out of a 77 K10 4x4 truck. The front pad has F1006TLD and under that it has C9S118352.
With that suffix can anyone id this for me?????

Thanks