70 340 4 SPD Swinger

I started getting the new Legendary Interior finished. Also finished up complete rebuild of the steering column. Picked up the block and rotating assembly yesterday. Should start on the short block assembling this weekend. The U heads are almost done too. Someone said the x heads were correct.... but the second owner who bought the car in 70 said these are the original heads....dates line up with his info. I have never seen a 70 360 motor, what vehicle in 70 had a 360?