I tackled this problem once. Let me say unless you have a lot of patients,money and time, and the boat has some special meaning to you- it is not worth it. I completely gutted an 84 century mustang 195 down to the outer hull. It took months of weekend and evenings to get her tore down, rebuilt and ready for the water again. It also gets expensive to do it the right way. The proper wood, fiberglass and resin, foam, etc is costly, and when done you will have a nice boat, but still old as far as resale goes. On the positive side- it gives you the opportunity to set up the boat exactly as you want it - seating, livewell, lights where you want them without exposed wires anywhere, everything conformed to the way you want your boat to be. If you do have saturated foam, and plan on tackling the project- be 100% positive your stringers and transom, motor mounts etc. are still good. If they are not near perfect- they will give you trouble down the road unless you replace them now, then all your hard work, time, and money are wasted.
Just my 2 cents.......