Again, not being a fan of stock outdrive power steering setups, I would highly recommend the Teleflex 2.4 helm and individual rams for each outdrive. There is a conversion ram that goes in place of the existing steering actuator, making for a very tidy set up. You'd only want to bleed the rams once though, if your engine area is anything near as tight as that pictured above. Cost including rams helm, hose and labor will be in the $2K range.
Thing is with the stock steering you have TWO systems in place, the push pull cable and the hydraulic ram. To my mind it is very overcomplicated and subject to too many failure points (v belt, linkage, fluid loss etc.) The hydraulic has two moving parts, the helm rotor and the cylinder ram. They are very robust and trouble free steering systems.
(Bob, if it were me, I'd make the jump. You won't be sorry.)