When I was into cars, I used to get perturbed at people who'd swap Chevy engines into Fords. Then I realized that it didn't matter, especially when it came to engines that were getting rare. It was great that those engines were being used and seen, instead of a cookie-cutter 350, or other "easy" engines. Part of the reason I stopped with the car thing was the shows themselves, the same model cars over and over, done the same way. It was utterly boring. I loved the oddballs, but those cars were shunned when they'd show up.
It doesn't really matter, do whatever you'd like, keeping every bike as manufactured or period correct is boring. Do what makes you happy, don't be the fart huffers that have a heart attack over the right shade of paint or other utterly meaningless minutiae.