2mm isn't really that big a deal but can be dealt with. Adding an 1/8 to 1/4 turn to the non-drive side will have no major effect on the overall spoke tension of the drive side. A 1/4 turn if that much is needed will increase the drive side by 1-2kgf which shouldn't be enough to really matter. Just do all the NDS 1/8 turn and then go the other 1/8 if needed. Wheels list a max tension but I know I only worry about building close to that limit, not hitting it. If the wheel says max 120kgf spoke tension I build till it all feels good and stop somewhere close to the right tension, usually if I've hit 115kgf, then its good enough and there's room for a touch more.