360 balanceing
Whoa Joe. Just vist the machinest and have a talk. Or call if there far. The machinest will ask you one or two questions. One being, "Is this 360 going to be a internal or external job, (2) manual or auto trans?"
I did a .030 over 318 and 360 many years ago. These builds were super simple piston only. This caused the engine to shake. It was even hard to get a screwdriver into the carb slot to tune. Get the picture?
Now drive down the road with the ever increaseing shake.
The new pistons added weight throws everything off. Nothing else that you do shy of rebalancing will fix the problem. Not re-balancing will damage parts and wear out the bearings faster.
So just call'em up or vist them and have a short talk.