I like the idea of a 12rn on a 9610, especially for 150 or bushel corn. With an 8rn on it with that corn you could practically put the hydro lever all the way ahead in 2nd gear if you wanted to. (At lesat I've done that with ours before!)
However, as far as I know there were extras for the 9600/10's equipped for a 12rn. I think the final drives were planatery and the feederhouse lift cylinders we considerably larger, I do not know if the hyd. pump was any different. If yours is not equipped for a 12 row, it probably will not lift it. Perhaps you could check a salvage yard for the things you need.