OK, i took this approach with my Challenger.
if the NOS part was obscenely expensive, i used repo parts.
if it's visible and you can noticeably tell the difference between the two, I went with NOS
i looked for a lot of original parts, cleaned them up and they looked and are correct.
i wanted to drive my car, so ALL NOS parts would be a waste of money for me.
i only had two frivolous NOS buys so far
NOS left fender - $700
NOS 14" trim rings - $600
as for the judging thing, i can give a rats a** what people think and say about my car. it's mine and not theirs. if they have a negative comment then go build you own. judges can keep all the trophies, I'm out to meet people and have a good time!