If you want to sell it, then sell it on as is basis. The next buyer can do what they want with it. If you want to keep it, replace the roof and necessary parts, and use it. Best show it to a qualified denter and get estimates for proper repair. Body change is not advisable because pajeros are already slow in the market, body changed ones are sold in the same price tag as ncps unless the buyer is a unique one and falls in love with the vehicle.
PS If you plan to keep it, get it thoroughly analysed mechanically too, things might probably have gotten damaged