Paul,
If the Pista is Brian Keast's former track bike--and if I didn't have such a bad memory--I would be able to tell you what it looked like back in the day. (I have some pictures of the racing scene then, but none from the track.)
Brian and I raced together--our cohort of young racers were lucky in that the wooden track built for the 1954 Commonwealth Games (at China Creek) was refurbished in 1970--with a lot of volunteer labour and Federal money. (It has since been torn down, and replaced with the modern covered track in Burnaby.)
Resurfacing the track sparked a resurgence in track racing & we all went out and got track bikes... so I would not be surprised that the Colnago would date to the narrow band 1971-72 Matthew has proposed.
Dean Kernan
Pomona, NY USA