The '66 lenses (all of them) are '66-only. The uppers are available as nice quality, inexpensive repro items out of Mexico. AFAIK the middles and lowers aren't being reproduced, but I could be wrong about that; need to check one particular cattledog when I get back to homebase tomorrow.
It takes effort, skill, materials, practice, excellent originals, and a lot of time to make repro lenses good enough for people to want to buy. One technique is described step-by-step
here. Figure out your costs for materials, supplies, tools, equipment, and the value of your time and you will quickly understand why most good repro lenses cost a lot of money.
As far as the amber idea raised by SSVDP: Good idea if it's done right; see
here (that's my old '71 Dart in the top pic, also I wrote the article) and
here (hookup info on how to have dual-function turn/backup lights).