Re: 1975 Starcraft 16' American Bowrider?
It really depends on what you have under your covered bow. You may need to add an elevated deck (one step up) for strength and to accomodater the seating, then build the seat up from there.
Your primary concern will be strengthening the bow area to make up for removing the bow cover on your boat. Then it will be your seat height and design.
Start reading through the bowrider restorations in the completed restorations forum to get ideas on what you need to do and how you want your boat to look:
Completed Boat Projects
One big mistake I've seen several people make when doing this project is cutting the bow cover out too close to the hull. You need to leave the same amount of width from the rub rail to the cut out as the gunwales are, so you can make the gunwales go completely around the boat in the front. This is important for strength too.