Saw a C.F. bumper at MSA.  Doesn't fit '73's.           http://www.thezstore.com/page/TZS/PROD/classic02n02/50-1752

They say you can swap 71-72 bumper brackets that fit the bumper but they need  modification, without explaining the modification except to say cutting and bending is required.

I have some experience with fiberglass and have some carbon fiber cloth so wonder if I could make a CF mounting plate on the CF bumper and use the '73 brackets instead of buying and modding 70-72 bumper brackets. 

Feel like I brought a spoon to a fork fight.

The 73 had a different mounting bracket because they started with the heavier bumpers.

That is why the bumpers wont fit. You will need to make a set of brackets to convert to the smaller lighter bumpers. 

When I mounted an early 240Z bumper on my 73, I just had to get the early mounting brackets.  They are available. http://www.thezstore.com/page/TZS/PROD/32-1060

You'll also need spacers on the sides of the bumpers. I just found rubber bumpers on McMaster and trimmed them to the thickness I needed.

More info here: https://fiddlingwithzcars.wordpress.com/2014/01/20/installing-the-front-bumper/

Thanks, lucked out, MSA had that stuff.