Rally cams, mt23 is a nice rally inlet cam and the 21 I can't remember off my head iirc 23 is 11.25mm and 280ish deg duration I will check tomorrow on that and try find the info on the 21.

I imagine the 21 is a exhaust cam to match the inlet circa 9.5mm and 256deg

Would have been in a group a engine I beleive