When I retired I helped a British Superstock rider for a season and learnt very early on not go rely on the factory markings for the rear axle.We used a Ronometer,which is basically two lengths of square section alloy tubing that were clamped either side of the rear wheel.The other ends of the tubing would reach either side of the front wheel.Adjustments to the rear were made until the gaps either side of the front wheel and tubing were equal.You had the opportunity then to make your own reference marks on the swing arm. Don't know how much they cost, but would be easy enough to make.
Whizz kid sitting pretty on his two wheeled stallion.