Rich, the bumpers can be a problem in some states. One owner of a beautiful Euro bumper GT5-S in Hawaii was denied registration until he fabricated full bumpers (front & back) from pipe! This in spite of the car being all stock, nearly 30 years old and having been registered for years in the same area! Apparently the so-called king of registration on the Big Island decided to exert his nickel's worth of authority and make a beautiful historic vehicle conform to his idea of a 'legal car'.
This of course screams for a lawsuit but not everyone has the dollars to throw at lawyers and courts. It was a decade ago and with the disbanding of the Hawaii POCA Chapter, I never heard how or if it was resolved rationally.