Once you're comfortable with the rough numbers, then you can complete the sale and move on to detailed plans and estimates. Anyone who has done several major refits can fairly easily rough out the overall cost. And, of course, there is always more to be done than you anticipated. The tendency is always to try do more, to expand the project, and it is here that you're planning and cost controls will really pay off. The most successful jobs are done with a plan and a budget, for the budget is what will keep you from straying from the plan and opening Pandora's box.
Every boat has one and it helps to know where it is and keep the lid on tight.
Unless money is no object, toe the line between what needs to be done versus impulse and vanity decisions. Stick with the plan and save the options for later - if you're still within budget. Many refits got off-track because the owner became distracted with luxurious interiors and fancy gizmos while neglecting a pair of worn out engines or other important systems. For this reason it is imperative to schedule all work by priority. Restoring major systems to reliability always comes first, before considering cosmetics and amenities.