Yes, Rocky is you best contact. My memory and time to help you is limited at the moment. Briefly, I can tell you that Zirkelbach, Keagan, and I did the FD of the upper Rio Urique in the late '80s. The shuttle is pretty challenging. The banditos were totally in a rage throughout the canyon and its rim at the time. And the boating was certainly class V/+ much of the time. Lower water is recommended. We did our trip betwenn x-mas and New Years day It was 6 days on the river and at least a couple of portages, but tried to stay in the water to avoid the banditos that were robbing, raping, or murdering everyone they encountered in the canyon. It was a great adventure and we barely managed to avoid numerous debacles in the entirety of they expedition.
I believe that Rocky and others have since explored the area and Rocky has an excellent website with everything you need to know probably.
No risk, no reward. It is not that we have to, it is that we get to. Preparation and education are essential to self-confidence and success. - KV
"If there is no risk there is no adventure."- Bill Briggs