Quick update. Got my Uplander a few weeks ago. As expected from all my reading, it was craaaazy stiff. Required an obscene amount of force to open and close it.
I spent a few hours working on it though, and wow, it's made a world of difference. I ended up pre-emptively ordering improved firing pins and a lighter lever spring from Long Hunter Shooting Supply. Lightening that spring made a significant difference. I also borrowed a friend's Dremel tool, and using some simple felt polishing wheels and red compound, I did some light polishing on the mating lugs between the forearm and the receiver. I could have probably got more aggressive in these areas, but was hesitant to go too far lest my ignorance overpower me and I end up altering the function of the gun.
The BIGGEST difference made was by far to do with the extractor. I removed the extractor and buffed the shaft of it using 600 grit sandpaper. I then used a file and carefully shaved off tiny bits of material from the sides of the extractor and from the area near the chamber openings where the extractor was catching. After putting it all back together, I am confident that this was causing the bulk of the difficulty in opening and closing. The gun can now be opened easily. It doesn't quite just fall open when you depress the lever, but requires no more pressure to cock than the old Lefever Nitro Special did.
Overall, I am very happy with how it turned out. It's definitely not a work of art, and you can definitely tell that fit and finish on these from the factory is not amazing. But I am pleased with the opportunity it gave me to grow in my novice gunsmithing skills, and how spending just a few bucks and a few hours at the bench really transformed this thing into a keeper.
I also like how simple the gun is to work on. The action is simple enough that even as a true novice, I feel like I could diagnose and fix anything that goes wrong with this gun. Really happy with it.