The San Luis Valley was still under the District of New Mexico, HQ in Santa Fe, in 1862. The reports/messges etc. you are looking for involving Ft Garland are in those records. Some of the letters are in bad shape and unreadable. These are found under "Letters Sent," "Letters Received," and "Register of Letters Received," Headqurters, Department (later District) of New Mexico. They are on microfilm.M-1088, M1097, M1120, NARA, RG 393. There are about 30 reels to cover the Civil War, but you could get the 1861 and 1862 ones, maybe 6 or 8 reels. The main reports are by Hodt and Eaton and there is other stuff.
There is a complete list of those arrested at Ft Wise in the Rocky Mountain News 21 November 1861 and a complete list of the same who busted out of jail in Denver 27 February 1862 in the 28 February issue. That's on microfilm too.
I haven't been able to follow it up, but your info on Heffiner really, really has me fascinated. I just came up with another complication, John H. Gregory disappears off the earth at the same time as the Mace's Hole bustup. I'm going to post that as a question separately. I wonder if he was connected to Heffiner somehow?
Thanks agai
Earl Pittman