So ive got a syntace headset and a spare crown race from a hope headset lying around. The hope one has an integral seal in it. Is there any reason why i shouldn’t use this with the syntace headset? It looks very similar (apart from thickness) but i am unable to measure the angle.

If it’s a 1.5” cup you should be safe, all of them are 45 degrees; for the smaller bearings Hope has 36 degrees on the inner bearing race, while Syntace seems to use 45, so the crown race won’t work.