I've only seen pictures of that model, but all have shown it in that same orange, which looks amazing with the chrome lugs. I want one!
IIRC Centurion had a 'Professional' top model at one point then the 'Semi Pro' replaced it later rather than being the second model in the lineup.
There is (maybe you already found it) a 1979 Centurion catalog online, at the essential velobase.com site. It has the Semi-Pro, but a later version (and not that pretty orange either).
http://velobase.com/Resource_Tools/CatalogScans.aspx
BTW that's one of the Sugino 'Mighty' cranksets (Mighty Competition, Mighty Tour, Mighty Mighty, Mighty Mouse, etc). It was a Campagnolo copy, hence the crown and fluting, but a desirable set itself nowadays.