Here's a German 73 with custom bumpers: If you don't want to cut up your bumper, I think the best option is to put the bumper closer to the chassis. This improves the looks of the 73 IMHO. Here's mine with full bumper, but without the "impact energy absorbing units", back in 1995: Remove the absorber (red), cut off the white part on the blue plate, between the green and the blue parts you have to get a piece of tubing with the right lenght, (measure and decide for yourself what you think is the best look for your car) with a plate welded to both ends with slots in it for adjustment.
