Your paint scheme looks very reminiscent of one of my bikes. Mine is a 2001 Aluminium Dream Lux with an "LX" paint scheme. I think this paint scheme is quite achievable for an amateur painter yet it looks impressive. I know there are lots of Colnago Decor paint schemes.
I also think the entry hole for the rear brake cable is interesting. I have 2 Colnago's with the entry hole on top of the top tube - a 1991 Super Piu and a 1991 Conic Total Spiral SLX. Quite often Colnago's have the internal rear brake cable entry holes on the lefthand side of the top tube. I agree with your frame build estimation. The features of your frame tend to indicate a cheaper build and either an International or a Super Sprint would be pretty good guesses. It's a nice bike to own.