Jim, my thinking on this, is that the seat should be recovered in new leather. Rather than spending the time and money on repairing an ols worn out seat by sewing patches that will make a weak spot on the seat, and trying to match the dye, hoping that there will be no crocking in the future, is just not as wise to me as recovering in new leather.
If it's just a black leather seat, then all you would need to do is use a thick chap or garmenbt hide to recover it with, and in the long run youd get a much better result.
Ken