The theory is that both of these methods should produce the same results.
The only potential pitfall is if the position of the rear wheel isn't central in the chassis, in which case the only remedy would be to add or subtract axle spacers until it is as I doubt you'd be able to change the drive pulley on the bevel box!
The rear wheel should sit central, meaning that either lining up the belt run or the wheel 'twist' in the chassis would be correct.
Not sure if there's any play in the Noise/Vibration/Harshness mountings to the bevel box that would interfere with accuracy here - maybe someone else does?
