A retail number for an unrestored Bowser in that condition goes for around $750 - $950. Make sure all the chrome trim is there. They rot from the back and fall off.
It’s very hard to give a number on a restored one for you. Depends how good the restoration is, the brand, original parts or repop, original pump plates or repop, and the platform you use to sell it (CL / FB, auction, etc). There are too many factors.