The more meat in the bores the safer it is to add more boost, so depending what you can get acsess to or how much boost you plan on running that's a starting point.

Can grinders can grind up a can optimized for Turbo engines, they have I believe they have less overlap or something. Balancing an engine should be a no brainer, it helps lengthen the life of the bearings and probly the rings to some extent. If you are are after torque and drivability I may suggest to not lighten the flywheel when balancing, but its more about what you want to do with the engine