Here are a couple of photos of my "Mystery Colnago". A few similarities to the OP's bike, and a few differences. As mentioned mine has an octagonal fluting, while the typical Master has 4 sided fluting. Only the downtube is fluted, the TT and ST both are round. Clover on seat stays, brake bridge, and HT/DT lug.

I can't guarantee the paint job is original, although it doesn't appear to be a recent paint job, and all script is stencil painted rather than decals.