Since you want the tilt steeting, the helm unit is different from the base fixed unit.
The Baystar is a less powerfull and less costly version of the Seastar, but in the future will not be good enough for higher HP motor which is readily so with the 20 footer. So consider it now.
Hydraulic steering is very expensive relative to mechanical.
The helm unit you saya you want is a tilt one, more expensive then the usual fixed on, and mdoel of helm unit may be a choice as to surface or behind the surface mount, others may be able to have a photo for you or say so from theirs, of look in catalog of boats on Grady website for photo or call Grady HQ on it too, besides hose length. (an extra foot of hose length is never a bad idea by the way, it will lay down below the bridge fine).
The ram in back is standard based on motor model and year, two hoses of given length, the helm unit, fluid and instructions. The kit will not be a packaged off the shelf one price deal as you want a tilt unit, so it gets to be customized but no big deal. Once the helm unit is picked, there is a Seastar distributor/retailer by me I recommend and have used for plenty for my onw boats, can PM you with contact, he can price up what the cost is and answer questions. If you are a DIYer you can do it, need new mounting on console - mounting not the same I bet as what you have now, and step by step fill and purge instructions. hydraulic steering is like night and day to what you have now, it is not power steering, but much different. Same steering wheel works, it has a woodrift key and taper fit. Dont loose key, If in trouble getting off, get back here for advice.
Keep old mechanical steering system as one day if selling boat and you prefer to keep the (expensive) system to take to next boat, convert back ! Can readily sell it used too!
As I don't know Baystar system, above applies to Seastar.
Good luck.
