I'm into my bumper conversion. Rear Bumper (pre 72 style) first. It seems to be very slow but I want it right. With the two pieces of the bumper together and fitting it to the body, I noticed that the bumper has a very slight bow up in the middle. I looked very carefully to see if it has possibly been bumped and bent but it does not look like it. Is the bumper suppose to have the slight bow or should it be flat. If flat is there something that needs to be adjusted with the three carriage bolts.