You did right, getting the higher quality horn for your first attempt. Cut your scales to size and slightly over finished thickness, before straightening them, because when you cut your scales out, they may warp again when released from the supplied piece. Be sure to use a proper wedge and not a flat spacer. Your finished thickness should allow the scales to flex inward to the razor pivot, after being spread outward by the angle of the wedge.

Horn can be hard to work with but it can make some beautiful scales. Boiling or steaming works. Heating in an oven works. Slightly over-correct the warp so it can spring back a little as it cools, which it likely will. You may not get it flat enough to suit you in just one session. Or you may get lucky and get a piece of horn that cooperates fully with your artistic vision. You never know, with horn.

Camel bone makes nice scales, too. At first glance it looks a lot like ivory. It is not quite as springy as horn. And some woods are nice, particularly ebony, ziricote, birdseye maple, etc. But horn, especially translucent or honey horn, really looks nice. Drills without shattering or chipping. Sands and polishes easily, If you can tame the warp, everything else is easy sneezy.