Hi- ongoing restoration of 1984 Ross Compact 10-speed; I have a shiny replacement chainwheel for one-piece crank I "must" swap out with the existing less-shiny chainwheel (keeping all else from the old set).
I can't find or determine right tool to dissassemble the existing set to swap out the chainwheel.

Local bike shops too scared and/or uninterested and/or lack obsessive compulsions to properly assist.

I acquired a 1979 Shimano service brochure detailing entire system and process, but even so... This is the sole remaining item keeping me from completing this project and riding my bike again. Help? Click pic to embiggen.