So here is what I've learned about fenders. If you are doing a concourse/rotisserie restoration, or have the money, just buy a good set of 71 fenders. You'll save yourself time and hassle. Im poor and am not doing a high dollar resto, so I opted to modify my 70 fenders. Here is what you need to buy.
It's all pretty straight forward, I just highly recommend that you do all of this and test fit your grill before sending the car off to paint (I wish I had). I had my grill in and out at least four times before I had it all lined up correctly. Note that there is about a 1" lip that hangs down where the header panel and fenders meet. You will need to grind this out. This is where it was before I removed it.
Unfortunately for me, I did not know I needed the backing plates for the headlight bucket brackets until after my car was painted and almost completely assembled. Instead of trying to drill, grind, and then weld in the new pieces, I found you can get it all to fit with a little bit of massaging from the grinding wheel and drill. I do not recommend this option, please plan better than I did. Here is what I had to do to make it fit. I've circled the holes I cut and drilled. Once you've done this the headlight can mounting brackets will sit just far enough back that everything works. Just note that you need to have your headlight wiring harness pulled into the proper locations before installing the grill. You cannot do it after as there just isn't room to squeeze the headlight plugs between the fender and the mounting bracket.
And this is what it looks like after installed.
One last thing I'll mention is that I'm very impressed with the metro reproduction grill assembly. Not only does it all fit together very well, but it seems quite durable. For as many times as I've had to install it and remove it I have yet to have any worries about it breaking or the paint adhering to the plastic. Great product.
And the money shot.