I'm just saving and restoring a Miyata bike from ca 1990. I think the model was called Sport Cross but I cannot find it in any old catalogues. I find the model but the info doesn't quite match up. For example I can find a Sport Cross from 1991 but that one is with 700c wheels and mine is for 559 wheels.
It's a butted steel frame and all I know is that the fork is CroMo. The stickers on the frame is too worn out too see.