318 build up

No adapter is needed to bolt the grand to the crank. You just have to make sure the back of the crank can accept the trans into it. This is called a pilot hole. A bushing goes inside of it.

When you balance a crank, you also balance the rods, pistons, rings & bearings, damper & flex plate or flywheel. Some shops I know also want the torque converter as well along with it at the same time.

All 273, 318 & 340 engines are internally balanced. (Except a '73 - 340 engine but that can be changed) all 360 engines are externally balanced. LA & Magnum engines have different external balancing weights.