I've not tested such an OAL, but the 1235 seems to fill the magazine pretty well already.

I tested 6.8 grains of Unique, averaged 1001.25 fps.
That'll do for me. These are "compliance" loads, not my regular stuff.
They shot reasonably well, and to about the same POI at 25 yards.
Looks like I'm good to go.

Thanks, everyone, for your assistance.