You'd probably have to cut the front supports off of a GC and weld it over, cutting the GD fenders should be easy enough, maybe some fibreglass about it. The hood is another situation, you may get lucky and be able to use it or skin it over to the GD hood without too much of a problem, worst case is you have to make a fiberglass hood. it doesnt seem that hard, have you seen the bug eye to eagle eye conversions?