I just saw your post about your wheels.
I tried using wheels on the mill frame but I didn't like the way it caused the mill to rack and the way the wheels applied too much pressure to the side of the log rails.
To eliminate racking on the mill frame, the best location for wheels is in the same plane as the bar.
This means the reaction force to the cutting chain is in the same line of action as the wheels and this prevents racking.
Racking will happen on any mill and I see it happening even on my small all steel mill using the 441.
Long terms even if doesn't look or feel like the mill is racking, wheel location out of the plane of the bar will contribute to bar groove wear and chain drive link wear.
The other problem wheels (even if they are located in the the plane of the bar) is that the wheels will sometimes ride up or down the curved sides of the log
This problem is worse when the bark grain ridges assists the rise or fall of the wheel.
I tried to solve this problem on the BIL mill but using 2 sets of wheels above the bar and 2 sets below the bar.
When cutting the top half of the log (see A below) the best place to reduce the "wheel riding up the log effect" is to locate the wheels as far down on the flat side of the log as possible,
So this is where I placed a set of wheels - see the black lower wheel.
When cutting the bottom part of the log (C) the upper or white wheels help with this cut.
The smoothest/best cuts happened when the widest cuts are being made in the middle of the log (B)
On my small steel mill I use a single pair of wheels that can easily be adjusted and even flipped over so they are either above, in, or below the plane of the bar..
These work really well. I also have a longer set of shafts than be used for bigger logs.