The modern way is to solder the tone pot up to the outer lug of the volume pot. The 50s version is to wire it up to the central lug of the volume pot. Which is best depends on personal preference really. Also to some extent your guitar, pickups and playing style may influence your preference. Whilst it is true that the modern wiring version will maintain the overall volume better when you roll down the volume, you are sacrificing a bit of the high end. If you have a bright pickup then the modern wiring option would 'fix' this and avoid the piercing tones when playing with less volume and the same amount of treble! Alternatively, the 50s version keeps the amount of treble the same but you do lose a bit in volume as soon as you roll down the tone pot.