Help with sewing----its for a diesel!

[MS Fowler]

Sorry if these seems off topic, but its for my 300SD and this is the best forum on any Mercedes board!
I need to restitch the rear seat back for my '82 300SD. The stitches came out. The leather is not torn. I have treated it with leatherique to soften it up so it doesn't tear when I reassemble. I need to restitch three areas--the center section at the top of the seat, all the pleats ( the backing rotted away, and the fabric that secures the cover to the frame. All places look to be straight stitches at about 7.6 stitches per inch. I am thinking that if I can find a machine that will adjust to that stitch length, I can simply use the old holes. Has anyone tried this? Any ideas on thread to use? I may have to do it by hand, but would rather use a machine. Is this stitch length common? Since I want to reuse the old holes, is a walking foot, or commercial machine really required. Seems to me that most of the work ( punching thru the leather) is already done.