Colorado emissions laws

Hopefully a Colorado resident can give me some info regarding emissions requirements and procedures:
I am looking at a few employment opportunities in northern Colorado,
specifically the Denver area and Loveland.
My current inventory includes a quarter-million mile '75 Volvo and a very much altered '81 Chevrolet passenger car. The Chev will pass (by a healthy margin) on the basis of tailpipe emissions alone (or at least it was clean before I tore it apart again), but it certainly does not retain its original emissions equipment. As for the Volvo, it's obviously completely unaltered, but if it actually passes an inspection, I'll eat the tires for dinner.
I'm certainly not a tree hugger, but I do appreciate the need for air quality managment, particularly in and around Denver. That said, would I run into California-style "visual equipment inspection" hassles with my Chev, or is its actual emissions the only concern? Does the generic 25 year requirement for exempt registration apply in CO? It will be some time before I put it back together, but it will eventually get a clean, strong fuelie and six speed to serve as daily wheels once again.
When I purchased my Volvo, it had quite a collection of smog cert stickers (it came from Colo), but the newest one was from several years ago. Is this vehicle no longer subject to smog regs? I was under the impression that every vehicle must be tested, regardless of age, unless it was electric, less than four years old, or registered as a specialty vehicle. I wouldn't think that the previous owner of the Volvo registered it as a Collector Vehicle...
Thanks.
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