I have heard the same thing about enlarging lenses making great macro lenses and that could be an option, given my current availability of gear. But how are they for copying a 1.5m painting, for instance? And what f.l.; 50mm, 75, 135?
Your idea of using b&w film at first seemed impractical, but taking two pictures, one digital & one b&w film, would be an excellent archival asset.