hey steve,i narrowed my steel bumper not long ago and i took 3/4 of an inch off each side.i wish i had just cut it down the middle #-o .it seemed to make sence that way when i narrowed the bumper filler.its less work that way.what i've done when i replace quarter panels is,over lap the new panel on top of the remaining section of the sail panel,then make one cut through both panels,pull it apart and remove the excess part.that way the two parts fit perfectly together.i did that with my bumper filler and just welded it up.i would rather just glass the middle of a bumper than two ends.you could cut it in half,bolt it back to the car positioning each half where u want it to line up with the fender&header line, having one overlap the other and make one cut up the middle and glass both sides together from there.just an idea.keep us posted.
CR