Eric,
We (The List) briefly addressed the component issue of 3Renshos maybe a month ago?
The ones I have seen (and own) have either been, all Campy; all Shimano; or a combination of the two (plus some other brands, e.g., Modolo, Nitto....).
I think a complete Suntour equipped 3Rensho would be just fine, but then, a "combo" 3Rensho would also be quite nice, and probably more the way they were originally built up? I suspect most (all?) started out as frame sets only and were built up by the various shops/owners who bought the frames?
Chuck Brooks
Malta, NY