I'd stick with the officially published data and do the first batch at 10.8 grains. Please check the powder level in every case before you put the bullet on, as everyone makes mistakes.

My Lyman manual also has data for a Thompson Contender that does 10.3-11.5 grains. The Contender is a break action pistol with a long, unvented barrel- effectively the same as a short rifle. If these loads are good in a 14" Contender they would be fine in a 16" rifle barrel. I'd still start at 10.8 grains though.

BB