Looks like a good canvas to work on!
I'd keep the literati vibe and firstly see which front/angle shows off the trunk movement best. Try putting wood blocks under the pot to test the angles. Then once that is set, i believe the junction of 3 primary branches needs to be reduced to 2 so i'd analyse which two will flow best together and create that nice line from trunk to tip - that might be an obvious "yes" to those branches but could also just be a definite "no" to one which is uglier than the rest. Then of those remaining two, decide which one is the defining trunkline to focus on and follow.
Established box branches are really stiff and almost impossible to move, often they don't have much taper too. To help see the structure I'd clear out foliage close to junctions, plucking a few of the little leaves in the first 2cm of branches to see into the foliage mass.
Not sure of the general consensus but as its an evergreen shrub and not a traditional bonsai subject I don't think box has many rules, you just want to stay away from the obvious and elevate it above any "pom pom" topiary style pads. I'd probably include deadwood/jins sparingly where it makes sense to help add age, boxwood jins are v resilient as the wood is so dense.
? Where would you start on material like this?
