A few engine questions

I think it's Hennsely racing ...there looking at all the 318's they can get there hands on. It seems that the factory has alot of variances in what sleves they used in the block. Some of the blocks, a selected few are bored over to 4.00 after they pass a sonic check and deemed OK for this use.
There making 4.00 bored X 4.00 inch strokers from the 318.

Otherwise, the less you bore a cylinder out, the stronger it will be. Thicker walls flex less and will have a longer life and a cooler running temp.
It takes a good bit more money to sonic check and then bore a teen out to 4.00.

The 360 differs with the journal size, oil pan and stroke of the crank. After that, there basicly the same. Engine mounts can be divided into 2 groups. Narrow 340/360 drivers side mounting points and 318/273 wide drivers side mounting points.
360's are externally balanced and the '73 - 340. (Some 72's, late year I'm told.)