Vic,
If I remember correctly, the Peterlongo series( also 8mm) headsize was more or less close to 8x57.If this is so, they could be made by turning the rim off 9.3x74R, turning new extractor groove,fireform, and trim to length.I will try to remember to check.BYW I know 9.3x74R is usually smaller than 8mm,but should fireform ok.
Mike