I had Dave Sullivan in Erie do a semi-custom for me a couple years ago. Time to completion was a little slower than originally anticipated (pretty common occurrence though in this realm it seems esp. for one man outfits) but its a nice shooting gun.
Dave Sullivan, Westwind Rifles in Erie - great guy & great gunsmith for a build.
Kevin Weaver, Weaver Rifles in Peyton which isn't Denver area, its East of the Springs - great guy & great gunsmith for a build.
Both are busy and you'll need patience but will be happy with the end product.
Second David Sullivan (westwind rifles). He’s finishing up a semi custom 6.5x284 for me now. I’ve had other work done over many years from bedding and trigger work to switching a safety on a shotgun. All good.
Another option is Harless Precision out of the springs. The shop itself is only a year old but the smiths (brothers) have a ton of experience, including working on Olympic Gold Medal rifles and national/world championship winning rifles for 1K yard shooting. They are some of the best shooters in the world themselves and have unbelievably fast turn around times.