Yup, that can work.
I'd use heat to even the limb profiles. You can either add deflex to the mid left limb (and produce a gull wing profile), or add reflex to the mid right limb (and produce a five curve profile). The gull wing will probably be easier to tiller. Plum works well with wet or dry heat and oil. But since the wood is green, I'd seal the ends and let it set for a couple months first. Or my other method for plum: rough it out and wrap it in plastic wrap for a week, than cut holes in the plastic for a week, and than unwrap it for three weeks indoors.
Either way I'd go semi-bendy handle design. And don't worry about the high crown, plum can handle it. Again I've never worked with American Plum, but with other plums this limb can easily give 60+ lbs at 28 inches with a semi bendy handle design....
Gabe