I don't think this is a good idea for a couple of reasons.
(1)Its been done really. Back around 1990-91 they traded 497 to the C&TS for 482. 482 is now running on the D&S, and the K36's are probably a better engine overall than a K37.
(2) C&TS already has 2 possible candidates for K37 restoration. The 497 is one, and it has run the most recently, but needs its FRA compliance, plus probably a full rebuild. 492 is said to have a decent boiler but it too needs extensive work, probably nearly as much as 497.
(3) 494 and 495 are unlikely candidates, but I say keep them around. You never never when money becomes available and someone wants to see them restored. Engines are a finite thing. Never going to be more than what is on hand, running or not running.
(4) If anything were traded getting a K28 on the C&TS would be more interesting but I doubt that would happen. Then you could someday have a K27, K28, K36 and K37 on the Chama line. However since the K28 cannot haul as much up Cumbres as either the K36 or K37 economically that trade would not make much sense. Also I doubt D&S would give up a good one(476 is not operational).
(5)I suspect after 489 is out of the shop this year, the C&TS will consider either 463 or 497 for their next rebuild possibly starting this fall. Hopefully by 2010 you will see both in steam if we are lucky.
My thoughts on the matter, FWIW...not much!!!
Greg