#1 Tip. Wait until July. By then the road should be open and you will only have to deal with wet roadway in a few places. Dress warm.
From Calgary I would do the first day down Highway 2 and make a stop in Nanton at the Bomber Command Museum and then cross the border at Carway. There is also the Remington Carriage Museum in Cardston to look at. Depending on how many days you want to do this maybe spend the night in St. Mary, MT and do the road east to west which will put you against the mountains most of the way. Then turn around and do it the other way so you can look over the very short wall to the abyss on that side of the road.
If you want to see more you can take Highway 2 back east from West Glacier and go through Browning and then 89 back to St Mary. Going through is a very important part of the directions, you really don't want to spend the night there, or much time at all during the day. It is what it is, a very poor reservation (reserve) town.
I lived in Browning MT for 4 years and that area was my back yard. I had a doctor I worked with that had a big family ranch east of Calgary on Highway 1 and I made quite a few trips up there to shoot her ground squirrels to keep her cows from stepping in the holes. I almost always went up Highway 2 unless I was going to Lethbridge or Fort Macleod then I would go over the border north of Shelby.
bob