Baker or some of the other cats here may have some input, but here are a few thoughts.
If you want to do power cleans, and in your mid-fifties you may not want to do them, you probably will not apply a 3/2/1 rep scheme. I would start with 5 triples and work that as long as I could adding one or two pounds at a time, eventually going to six doubles when it gets heavy enough and then eight or ten singles. By the time you are down to singles, you could go off of a clock, every 60 or 90 seconds. All this for sets across.
I am not much of a fan of stiff legged deadlifts, especially not for sets of 10. I'd consider dropping them, or doing something else. Baker does more DL assistance stuff and may not agree. Also, what is the difference between SST and STT? There seems to be a lot of complexity here and I just did some deadlifts this evening myself, so I am not up to the task of looking more closely at this. I am going to punt on this and wait for the others to chime in.