…Asian plums or European ‘prunes?’ I’d say either will respond as do apple whips. Just cut the whip off at the height you want your ‘highest’ branch to take off from; all others will obviously emerge from the buds below. But you don’t want to leave the Terminal bud at the tip of the whip; it sends a growth-inhibiting hormone to the buds below it – then heads straight up, with few if any branches.

If for any reason you’d like your branching higher, just let the straightest shoot continue up from the main trunk for another season.