The trees are typical north Idaho pine and cedar. I'll be using a Granberg style Alaskan mill. Not Granberg brand, but an Amazon knock off. Also I might be using a Timber Tuff vertical mill. I had an area cleared for the shed/cabins earlier this year and now I have a pile of logs I'd like to use instead of bucking them all for firewood. We will eventually be putting a deck around the two cabins. I could get some of the decking out of these logs. If I need a 90 cc class saw, I guess I'll have to be willing to put out about $1200.
You will need at least 2 saws, ideally 3 if you're working with decent size logs.
(Small saw for limbing & trimming, medium saw for bucking larger logs & removing larger branches & flares, & a saw for milling)
For what you are milling a Husky 385/390 or a Stihl 660/661 should allow you to cut slabs upto almost 3' wide using a 42" bar & mill frame (you will loose ~6" of bar length to the mill).
If you only need to cut half that then as stated above, something like a 372 or 460 would likely do (& a second saw for trimming etc)
Unless you are only toying with the idea, or making a 1 off cut, a professional grade chainsaw tuned slightly rich & setup for milling is important if you want it to last.
You will also need PPE, wedges, files, log moving equipment, etc. Unless you are extremely proficient at hand filing a chain grinder is probably going to be a requirement too.
Check out the csmilling101 thread here, it's a gold mine of information