Kevin, the City of Boulder did not bring the engine back to Boulder.
It was saved through the efforts of Dr. JB Schoolland, who put up his own money, and then led an effort of fundraising by the citizens of Boulder.
But your point is well taken, he saved the engine because it was old #30.
But it is not at all practical to consider "backdating" the engine to it's original appearance.
This engine has a unique history in the world of Narrow Gauge, and needs to be returned to her appearance before it was dismantled.
After all, it retained undeniable elements of her heratige, from her earliest days, to the last days, covering so many of the railroads in Colorado.
For anyone interested, here is a link to a pretty comprehensive history of the engine, done for Bill White's RGS Technical Page: