El Coke,
The only plans of the K&J hoppers that I know of is the one I did to accompany Stan Jennings article in the Gazette. Unfortunately, I later discovered a couple of minor mistakes, but in general, it is accurate for the Eureka Hill cars. I understand that Rich Dunn is working on plans for the PP cars.
Eureka, Utah in the Tintic Mining District has probably the best preserved artifacts (ruins) in the state. The much more notorious Park City has gone the way of Telluride and Aspen, and Bingham Canyon is now either buried or a big hole in the ground. I understand that the surface works of two of the largest mines in Eureka may be open for tours now.
I might recommend another narrow gauge mining line for inspiration. The railroad of the White Knob/Empire Copper Co. at Mackay, Idaho. Two 23 ton Shays and a gaggle of cute little 10 ton steel hoppers.
Sam Bass