Roofline is not different but it takes some work to convert the car to totally remove the landau top, including body work and paint. You will need a set of trim for around the rear window, will likely need a set of hardtop opera windows, and a hardtop filler panel between the rear window and the decklid. You can convert your filler panel and opera windows, it's just a little more work. You will need to weld the trim 'rivets' around the rear window for the rear window trim clips. There will also be some holes you need to weld up. You will likely have to finish the bodywork at the seam from the roof to the sail panel as the factory often didn't finish it on cars destined for a landau top. The conversion can definitely be done but it is a lot of work.