Front tire

You can tell when a salesman is lying when his lips move. The 70 series tire is taller raising the front. Raising the front makes the bike turn in slower. The 70 series tire ought to be about 6mm taller than the 65 so you can raise the fork tubes in the tripples that much to compensate. Raising the fort tubes lowers the front.

I think many people run the 70 series without doing anything to the bike.

Putting a 60 profile tire on the front instead of the 65 would lower the front about 6 mm. There is no way to compenstate for it because the forks are already to the top of the clipon. Lowering the front that much shouldn't cause any problem with instability. Supposedly the 60 profile gives a smaller contact patch but on the street I don't think you will notice the difference.