Sorry just noticed you said he was working medium/elementry level dressage horses that have proper dressage training are normally fantastic to teach to jump cause they already know how to use themselves and often have a very defined bascule over their fences. So enjoy and keep us informed
Dressage or good basics at very min are what a good jumper should start with. A horse that can't canter on a circle shouldn't in theory be a fantastic jumper till he is balanced enough to do that. All simple really but you would be amazed how many people freak out cause their "jumper" can't do a full clean tidy course, but dare ask it to canter in a dressage arena well it can't but yet they still question why it isn't doing so hot. Give your horse a foundation and you will be away laughing, also some good advise is keep it small and simple people often push to quickly and scare the horse, more so with horses that show heaps of promise at the start.