While your general route is okay, some of the roads you suggest would be difficult to impossible on a loaded road touring bike. The road from Montezuma UT to Cortez is mostly or completely dirt. You could ride it on a road bike but it's a rather long distance over a dirt road without any kind of services. Following UT 162/CO41 to US 160 and then to Cortez would be easier on a road bike.

The biggest problem is from Silverton to Lake City. This is a very high, very rugged 4 wheel drive road that is a tough ride on a mountain bike. It'd be almost impossible by road bike. You could go south through Durango to Pagosa Springs and over Wolf Creek Pass to Del Norte or you could go north through Montrose to Gunnison and then to Buena Vista. Both routes have both pluses and minuses. The ride over Wolf Creek is steep and hard but pretty. Once in the San Luis Valley, I'd cross over at Center to Mosca and visit the Sand Dunes.

The route to Montrose goes over Red Mountain Pass which is both gorgeous and frightening. This route passes the Black Canyon of the Gunnison River which is narrower and shallower but steeper than the Grand Canyon.

Don't get me wrong, your route is good but the specifics require a little local knowledge to keep from getting into trouble.