I never got that tight with the stitch length when I was testing the 130-6 with embroidery attachment. The very fact that the machine and unit were working at all... had me elated. I probably would have gone further it had been my machine, but when it's for a friend I take it a easy. Your test runs look fabulous.
I do have to say though that you have me quite intrigued. Is there some thing in particular (that I don't know about) that has you shying away from using original Pfaff motors? Is it an age thing? a rebuild thing? Just prefer the new ones? I'm quite curious.