YOu can move the bumper in a bit, I've seen it done lots, and helped my dad do it on his '52. Unfortunately, due to the shape of the bumper you'll still have to make a filler pan to fill the space (can make one out of sheetmetal).
I wouldn't recommend using a torch for this though, use a grinder to cut and shorten the mounts, and a die grinder, dremel, or jigsaw to cut your filler panel. Torches are much too crude for fabrication like this.
