Key set options for alps are limited, I don’t know of any alps SA sets myself.
I do know that Signature Plastics, who manufacture SA sets, also create alps compatible keysets. Perhaps ask them if they can do SA keycaps with alps stems, the worst that could happen is they say no.
But actually I just wanted to say that Matias switches are incredibly wobbly compared to Mx style switches, and tall caps like SA exaggerate any wobbliness further. Just keep that in mind.
On a side note, didn’t someone create Mx style sliders for alps switches a long time ago?