Good plan. Satisfy your designer itch by reviewing it carefully. There are potential changes; define them on a revised drawing for your airplane.
For example, the P-mag wiring is drawn with fused bus power, which doesn't allow a convenient check of the self-power function. You may wish to revise the drawing with pullable breakers, or the addition of a power switches. Note the S700-2-10 switch as drawn makes no sense; the p-lead is grounded in "BAT". Nor is there a prohibition on switching bus power to "OFF" when the engine is running, as the note seems to state. Personally I'd install individual ignition power and p-lead switches, as it allows self power checks, as well as ignition power OFF with the master ON. A broken p-lead is much more of a hazard with a P-mag than with a standard magneto, as a powered P-mag will fire when rotated forward or backward, at near zero rate.
Before anyone asks, yes, I have found a P-mag with dead internal power during a pre-buy. And every airport has a few broken p-lead horror stories.
As you intend to use a B&C main alternator, redraw for the B&C regulator and eliminate the OV module on that supply.
There may be more, but you get the idea. You're not changing architecture, just component-related detail.
Next consider the physical location of every component. Physical location can sometimes drive a required change. Even if a location doesn't change the diagram, it's best to mentally establish where everything goes before drilling holes or cutting wire.
After drawing in all detail changes, and double-checking your work, I'm sure folks here will be happy to provide review.
Nothing inherently wrong. Just keep the loads truly essential, the absolutely minimum needed to get on the ground.