Not sure what you mean by power steering, but when I had the old V-4 mounted on the transom years ago, I rigged up a hydraulic steering system using some Hynautic parts to replace an old teleflex push-pull cable. I had a live well under port seat, but starboard seat was open to bilge for battery access, etc. The original system on my boat was set up for an OMC motor and had the push-pull cable anchored to a pivot on the transom, with the cable/rod attached to a ball joint on engine tiller bar. The tilt pin on the old OMC's is in the plane of the transom, so if you have a single-engine transom cutout, you can't use the thru-the-tilt pin set up like the Merc's, where the tilt pin is a couple of inches forward of the transom. My cable attached to a SS rod and the sheath connected to an aluminum tube that extended thru a 4" square hole in the splashwell with a leaky flexible boot over it.
It's hard to explain my rig without some pictures, but here's what I did:
1. I used a hydraulic cylinder designed for use on an inboard with a ball joint on one end, attached to an angle bracket for mounting to transom.
2. Had Hynautic change the other end where the rod exits cylinder to the fitting designed to attach to the tilt pin on the motor, which just happens to have same diameter threads as the teleflex aluminum tube.
3. I then had the aluminum tube, that the teleflex cable attached to, welded to some aluminum angle brackets, drilled to fit over the top mount bolts on the motor where they came thru the transom.
4. I then screwed the SS rod from the end of the teleflex cable to the hydraulic ram, screwed cylinder to the aluminum tube, and attached mount bracket on other end of cylinder to transom.
5. I rigged up a drag link from end of the ram rod that extended out port side of the aluminum tube to the engine tiller. The drag link could rotate and pivot as the motor turned and tilted.
I know it sounds like a Rube Goldberg set up, but it was 100% reliable, and a big improvement over the push-pull cable, since all relative motion between the motor and steering mechanism was accomodated by the drag link! It totally eliminated the pivoting cable/rod assembly and the leaky flexible boot. The hydraulic cylinder was tucked up out of the way against the transom, just below the stbd seat. I covered the big hole where the boot was with some teak trim with separate holes drilled in it for the steering cylinder, wiring harness, fuel line and throttle/shift cables. The whole works was 100% watertight, so I could have splashwell completely full of water with no leakage into bilge! Like all hydraulic systems, it totally eliminate torque feedback from the motor, i.e., the helm would stay where it was when you took hands off wheel. It also moved the motor completly from stop to stop, which my new Sea Star system does NOT do! (I'm only getting about 75% of the full pivot that motor is capable of! Has anyone else noticed this on the Sea Star system?!)
I think I still have all the original hardware, so I'll try to dig it out tomorrow, lay it out, and get some pictures of it that I can post.
I think Hynautic was bought by Teleflex, but I suspect most of the parts for that custom cylinder are still available via internet, so it shouldn't be too hard to duplicate. If you want my old parts, I'm sure I could make you a good deal on them!
I think it would also work with the Sea Star Helm unit, except that you could use the rigid nylon tubing instead of the expensive rubber hoses, since the cylinder doesn't move. The only down side is that it's an unbalanced cylinder; there is a balanced cylinder that you could probably use with the rod coming out both sides, if you used more rigid brackets attached to the engine mount bolts. The brackets I had made up were only 2" x 2" x 1/8" aluminum angle stock; they were just used to support the tube. They would need to be much beefier to carry loads from the hydraulic cylinder. Denny