Master Cylinder Differences?

The 15/16th bore will give you better pedal control and feel. It gives you extra "leverage" over the wheel cyls..
Without the booster, you'll need/appreciate the extra advantage..

The extra travel you mention would be less than 1/4 inch with properly adjusted brakes.. getting no-where near the floor..

Try the 15/16, you'll love it,, so will your leg..

If you do a search, you'll find numerous threads discussing this.. cheers