Sorry, HK,
I didn't have a chance to talk to the honcho's, just the grunts like me.
As for Rollers, you CAN make them, using the right type of steel and Rockwell rating. As far as the NS Steam Program went, they wouldn't pay squat for anything, nor keep anything up, ask the T&P 610 boys. They offered to wear out the 1522 as well. I would take the NS Steam Program (Post Claytor) with a grain of salt.
As far as the Roller Bearings go, we (UP) swear by them. I would incorporate their design unless requested not to.
But I digress, I guess trying to create a reliable operating mechanism is not "historically accurate". Remember, advancements in Land Based Steam technology stopped cold in 1952 and is only now being resurrected in Europe. So why not try to incorporate the advances in metallurgy and engineering from the past 50 years? If you're going to do it, do it right.
If you want a historical recreation, warts and all, then have fun, but expect all of the shortcomings and drawbacks that plagued the originals. I would rather invest my money in a more reliable piece of equipment.
Rick Steele