Presale Renovation w/ Investor and seller

Is there a contract in Florida that someone can get into that protects both sides in this situation I am about to explain. A son inherited the home of his father after his untimely death and when he went into the house it was completely uninhabitable. His first intention was to just let the bank take the home. But an investor offered to pay for repairs, pay him a flat rate. The seller would leave the mortgage in his name during this process but the investor would pay the monthly mortgage. But when the home was sold the investor would keep the profits.