Peter Soderlund said " ...I bought it as a complete bike some years ago. It came with a complete campagnolo nuovo record group. The guy I bought it from told me ha had bought it from Gosta Pettersson, Gosta won Giro de Italia 1971 and he rode for monark. Maybe that was true after all. ..."
If it's all true.....
Just my opinion, your Masi is more interesting in its Monark plumage given the bike's provenance with a known racer, Gosta Pettersson, a winner of the Giro d'Italia,... he won the Tour of Britain, won the Tour de Romandie, won the Coppa Sabatini, placed third in the Tour de France, placed second in the Tour of Switzerland, etc.
Lots of Masi's out there. You can get a repainted Masi somewhere else but it is rare to get a bike in original paint from a racer with good palmares like Gosta Pettersson. You should clean it up, do not repaint, re-equip it with Campagnolo Nuovo Record, try to find some photos of Pettersson on that bike, contact his family, try to return it to its appearance when Pettersson rode it.
Do not repaint it to something it is not, and ruin your bike's pedigree, .... plus a repainted Masi is not an original Masi. Your bike is Gosta Pettersson's bike. If it has Pettersson's original paint, keep it that way. You may find that other vintage racing bike enthusiasts think it is more collectible and interesting than a standard Masi.
Looking via Google, I would guess he rode that bike in Sweden after he retired from professional racing, perhaps in time trailling in Sweden as he is quoted as saying he did. You could check with his family for starters.
Peter
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Peter Brueggeman
La Jolla California USA
4peebee(at)peterbrueggeman.com