Always good to have options..

If it were mine, I would go with the 'almost matching' back side scale. Mis-matching the vintage front with a new back wouldn't work for me. Credible patina and wear is hard to duplicate, though possible I'm sure. If for some reason it doesn't look right with the period correct back side, then do a full replacement even if it means losing the inscription. Though, inscription might be easier to have duplicated than the patina and wear.