WOULD IT BE A SIN

Only time issues rise is when you deviate from oem, is when you sell. If the buyer love all you did its great. If he wants the car and starts adding up all the costs and labor to make it like he wants, then $$$ start to get in the picture, usually big time.
I know so many people say this is just a hobby and we care less about $$ but not everyone has that luxury.
But, look at the big auction Restomod cars sell. Big bucks and growing it seems.