I'll build this up into an article describing how I tuned the Atlantic E6 4-4-2 to make it around the NPF Railway's O31 curves.  For now, though, it's mostly a slideshow of this lovely new loco! 

Front headlight includes lighted number boards on the lantern sides... nice touch! 

A view from below.

Rear marker lights shine out to the sides and behind. 

A view into the cab. 

The center red light on the tender only comes on when the loco is in reverse. 

A better shot you can see all 3 rear lights.. one through the windows of the ATSF wooden coach. 

Lots of overhang on this Ross O54-O31 switch! 

Another shot showing the extreme nature of this loco's overhang.  You can't even see the pilot truck from this angle! 

The "underhang" is not nearly as pronounced, especially on this Ross O54 switch. 

Some minor bending of the loco's rear detail is seen here, on the lower right-hand corner. 

To accomodate the NPF Railway's tight turns, these detail pieces were bent out and away on both right and left sides.  The shot above showing overhang on the Ross O54-O31 gives a good look at what these bent-out details look like on the NPF Railway.  If you are running on O36 or wider curves, you will not need to bend these out at all. 

Oh no, pilot's derailed!  This was happening about once every 6-10 times around the loop before I started modifying the loco.  First mod was just to fix the bent piece shown above.

Next I took off the pilot to do a little clean-up.  This pic shows the rear screw for the pilot in the mid foreground.  To get to this screw, start by taking off the center pickup roller assembly; it's already removed in this shot.  You can see the other pickup roller assembly in the extreme lower foreground.  The front screw for the pilot is easy to get to; it's not seen in this pic.

The attachment points in the center of the pilot truck itself do not need to be touched at all. 

The washer (background) seemed to "bind" a little on the square opening in the pilot's rear connection point.  This is supposed to float freely.  I used a small screwdriver to scrape the "flash" off the metal around this washer.  On re-assembling, I also flipped the washer to present the smooth-edged side to the sliding point; you can see that the washer has its sharp-edged side up in this pic.  I've got masking tape stuck on backwards, to catch the metal shavings as I work the flash off.

Next I tested and marked the pilot front for where it might hit the sides of the steam cylinder housings (I forget the correct term for these).  You might be able to just barely make out the light spot about 1/8" long on the cylinder centered in this pic, at about the "11 o'clock" position as it sits.  Even harder to spot is the matching light spot on the pilot truck casting, just barely behind the pilot wheel.

All wrapped up and ready to grind! I used a dremel with a diamond cutoff wheel to minimize pressure and strain on the parts.

Grinding complete.  It took just a minute for each of 2 spots on the truck.

All unwrapped and cleaned off!  Be sure to dust really well after using the dremel and before removing the tape, then again after removing the tape.  On re-assembling, use some grease on all the same spots it was on before, and on any spots that are supposed to move around.  If they already hhave grease, consider cleaning it off and applying all new grease: you just had bits of metal dust flying around, after all, and the existing grease may have gotten some grit in it.

The ATSF Atlantic E6 in action! Here it is hauling its intended consist, the ATSF Overton coaches from MTH.