How should I mount a spring horse to a hydraulic base?

  I've decided to take one of those spring rocking horses made by Hedstrom and mount it to a hydraulic salon chair base in order to make a neat chair.  What's the best way to connect the horse to the base?  Do I need some kind of metal bracket... or should I drill a hole into the horse so I can put it on the pump?

The horse's structure as you show it there is clearly designed to take the load on the tops of the legs. I'd make two, U shaped metal brackets to come up from under the horse to meet on top of the chair.