There are a few steel Colnago forks on eBay now. I wasn't expecting that. I think you want one fully chromed, sloping crown w/ a C and clover at the top of the crown on either side. The one for $179 and free shipping looks correct on my phone, though the chrome is rough. Steerer tubes can be cut or replaced if incompatible length for your frame/HS, not ideal though. I'd avoid getting a too-short fork and replacing w/ longer steerer tube if at all possible. Keep an eye out, measure the current steerer tube length so you know what to look for. A little long on a find isn't too bad, a little too short is. You don't want to ruin the chrome and you won't be painting to match the frame.
Check for ripples under top and down tubes behind the head tube with sight/feel/straight edge.
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After checking the $179 eBay listing on the home computer I don't think that'd be completely correct, but I certainly could be wrong. And it might just work for your purposes if steerer is long enough. I'd expect the tangs on the inside of the fork blades coming down from the fork crown to have windows, the eBay one does not (I'm using this listing as a reference rather than suggestion, but it might work for you depending on a number of factors). If you remove the rear wheel are the rear dropouts Colnago or Campagnolo branded? Fork ends should match the rear DOs re Colnago/Campagnolo, but whatever works for you - depends how picky you are.
I'm basing most of my guesses on my ~'82-83 Nuovo Mexico, so the fork crown style may have changed slightly, someone with more knowledge than I should know. Here's a couple shots of my fork crown for reference. Again, yours may or may not differ. I'd guess yours is closer to '85ish.
Another C&V'ers '85ish, similar paint application w/ different color. Decals are different, but similar with that exception:
http://www.bikeforums.net/classic-vi...vo-mexico.html