Any sailboat/ kyaking dealer with have lifejackets that are cut high. Murrays.com, teamonenewport.com, www.coliesail.com, etc etc all have many options. Almost all dinghy racers use lifejackets that are cut high and work well with trap harnesses.
I would not reccomend the inflatable kind, many big boat sailors use them (it's better than no jacket at all), but if you get knocked unconscious you are s.o.l. they make ones that inflate when they are in water but they are $$.