Not sure about that dcr it seems high. But have absolutely no experience with that kind of altitude. But usally a dcr of 9:1 is pretty much the limit for street use and sometimes alot less will knock with pump gas. Can you run 87 now?
That cam is not crazy big does it lope really bad. Cause it seems like a gear change is in order either way i would try and change the gears and see if it is drivable or just aweful with 4.11 i bet it would still be very happy on the street and track. I bet you could squeak away with 3.73s and be ok. Either way you got to do both but the gears is where the fuel milage will come from. I would rather deal with a tall gear then tear down a strong engine.