As you have probably gathered, it's a pretty rough time to build in the Flathead. Everybody in the building industry is extremely busy. We built 4 years ago, so my info is dated.
For dirt work / septic / drain field we went with B&F Excavating in Columbia Falls; super good guy, worked fast and was reasonable.
I live next to the owner of Bighorn Plumbing; he's a good dude, and I've heard good things about his work; I haven't had him do anything for me, but plan to if needed.
For heating, I would go to Performance Heating and Air; I know one of the owners, and he's a good guy. He's done work for several people I know, and it's all been well done.
I don't have anybody to recommend for concrete; the sub that did ours was okay...
Our framer was David Wells; I would highly recommend him; but he might be generalling some projects now.
It would be sweet if you could get 2 gun going up here. I know the guy that runs some of the shoots down in Bigfork, and it's probably something that's on his radar. Bigfork just re did a bunch of bays; from watching the 2G matches on inRange, the facility would not accommodate that number of stages with those type ranges, but some permutation may be possible.
A lot of people join ranges, and a lot just go up into the USFS and shoot in the woods. There are a couple power line cuts that allow shooting to 1000-1200 yards; of course, if you go east, you can shoot as far as you want.