You are way better off putting the inner fenders, outer fenders, hood, radiator support with radiator, bla bla bla in place and supporting temporarily - Get it ALL lined up, and then tack together a radiator support bracket (slot the holes!) . . . tear it all down and then do full penetration welds. You should work in mounts for the bumper while you are at it.
I used 3" heavy channel pieces welded to the clip horns going straight down to another piece of 3" channel from side to side. Caught the radiator support in the middle and then welded heavy angle to the cross peice at the right spacing to catch the stock bumper mounting brackets.
I didn't figure out how to do it until it was all mocked up and the bumper sitting on stacks of 2x4's to hold it in the right position (which is hard to figure out without the splash pan and grill installed too . . .
Ken
