early 260z and want to change to 240 bumpers

i have a early 260z. I am thinking about swapping the bumpers for some early 240z bumpers. Has anyone done this conversion before? How much work would it be? Would it look good? I want to do this because my bumpers are small, but not as small as the 70-72 240's and I want to put the Nismo mesh grill off a fairlady Z on my car.

Is there another way to be able to put that grill on without changing the bumpers? I would have to remove the bumper shock absorbers for sure. Any info would be great.

Thanks so much,

Ben