Your original hydraulic system should be intact. It just needs some TLC and a 250V DC inverter to power the two 15hp electric motors that drive the IMO pumps - only one really needs to operate. The hydraulic lines in the pump room and conning tower are metal pipes. I think the only flexible lines run from top to bottom of the boat, but they might be solid metal, too - I need to examine those lines more closely.
My biggest issue, so far, is finding a company willing to make a 2-phase DC inverter with 220 VAC going in and 250 going out. Usually they are custom made to your specifc application and each motor is 51.5 amps with a 1.2 hr variable duty cycle. Pretty oddball stuff.
Worst thing about the whole deal is the hydraulic fluid is really nasty stuff. Even the modern skydrol used in aircraft is toxic and caustic.