New here and looking for advice with my setup.

That looks like too nice of a car to mess with. Maybe my opinion but why? That car looks too nice to muck up. Not many of them left. If you want more buy a newer car.

The more you mess with it the less original could ever be.

Why would you care or try to convince him of getting a new car when he has the car to enjoy and modify as he would like. After all, it is HIS car and it’ll be HIS WAY, not yours. He wants to modify the car. If you want to have him keep it stock, perhaps you should buy it from him so he can roll the money over into a new car lock stock and barrel.