Hi Adam
27v should be plenty to run the leds, it all depends whether they're run series/parallel & what Alembics idea of current draw is, i suppose?
I have a warwick thumb with side leds that runs on 27v for the leds & 18v for the circuit with two separate battery cavities.
In theory it should all work for your Orion, it would just mean a couple of extra wires running through the bridge p/up cavity, if the power pack is at the back of the upper bout.
But lets see what Mica thinks....