The highest charge of Unique I have found in any of my older loading books with a 125gr bullet is:
Speer Number 8, with their old 125gr soft point with the round nose, 10.5gr.

And in my old Sierra book with their 125gr bullet 10 grains.

Most books show 8 to 9 grains of Unique as MAX.

I would definately start lower and work up.

There are so many variables, powder lots, different companies bullet diameters, different case capacities, different primers, and different cylinders/forcing cones, barrel diameters, etc. that loading a revolver to the MAX should be done carefully... VERY CAREFULLY...

I did a little of this with semiautos too, back in the day, but really there is a lot of increased wear and tear on the gun for an increase of 50 to 100feet per second over good safe full power loads.