There is really no limit to what you can do. You have a empty canvas so to speak. Storage compartments, live well what ever you want. Just be sure whoever you use makes it structurally sound and incorporates some flotation foam for safety.What size is the boat? Is the transom sound? If the transom is bad thats the first thing you have to take care of. For wiring depending on the size of the boat you likely will just have a 12 volt system to the front for nav lights and a trolling battery.
Really get it thought out so you can balance the load. You have batteries and a gas tank to consider in this.
I can tell you this, it will cost some money to do it right. However if you intend to keep it maybe it’s worth it to you.
Good luck!