In the true spirit of the internet, I won't really answer your question, but I'll provide some comment anyway. I've ridden in Colorado a few times. And the Alps and Dolomites. Climbing mountains is similar in western countries. Modern paved roads. Some roads do have steeper sections than others and some are longer than others, etc. But in my experience, the actual physical effort of climbing the Rockies, Alps, Dolomites was similar. The Rockies have fairly constant grades that are not bad. They just go on for 5-10 miles usually. Except Trail Ridge Road which is about 18 miles. It kind of wears on you after awhile, even if the grade is not bad. But the Trans Am does not go over Trail Ridge.
So, if you've climbed mountains before, you have all the information you need. If you haven't actually climbed mountains, then nothing anyone can say will enlighten you to what it is like. Its one of those things you have to do to understand.
My mountain climbing advice for everyone is to have the smallest inner chainring you can get on your triple crankset, 24, 22, or 20 tooth with modern triples. And have the biggest cog you can get on the back cluster, 32 or 34 assuming Shimano parts.