I've emailed Sampson - doubt they have any hanging around in their warehouse - but you never know. A couple of years ago they still had cleats for their old Stratics pedals.
Can aluminum be repaired safely? If I do replace I'll definitely keep them for the display case as they are pretty cool.
Roger - any idea on the weight of the Toplines? Not that it matters much for me but my dad built this bike as a weight weenie.