How much play in this pivot point is normal

to answer your original question, yes 1 person can do it, but to actually get it right you need two. First put somebody behind the wheel to floor the accelerator and adjust the carb linkage so the blades inside are vertical. Then have the accelerator wide open while you adjust the kickdown at the trans to be wide open at the same time. Then it is trial and error for fine tuning shift points using the adjustment of the kickdown rod at the carb.