" Are there any solid wheel & axle sets, Hi-Rail or Scale Wheel, available from any manufacturer that will fit the K-Line trucks, castings and gear size? I would like to know as much as I can about the wheel & axle sets as possible BEFORE I commence surgery on the unit."
I am not saying that there are not such parts - I don't know - but in the 3RO world, interchangeability and availability of mechanical parts is a fleeting thing, at best. And as for gears...well, even worse. Even like-for-like replacement parts from the importer disappear after a few years.
I dislike traction tires, too. But, they are a fact of life that I ignore, as getting rid of (replacing the wheels/gears/axles) is, essentially, impossible.
========> Other side of the coin: I have a beautiful, Max Gray L&N M-1 brass Berkshire (one fat-boilered loco), that I actually got free from a friend's estate. I would love to 3-rail it but only without butchering it.
I have solved - on paper - the lead truck wheel issue, the trailing truck wheel issue, and the tender trucks with pickups issue. But i can't find a solution to the Hi-rail driver (#1 and #4) flange/tire issue. The change is beyond my machining capabilities.
So, I sympathize.