I have a 63 and my frame rails are like yours. I needed more rad, but I went junk yard huntin for my new one. The one I found that worked had 68 Torino wrote in yellow across it. I bet I know who you ordered it from, somebody else was cursin a particular aftermarket company out tonight. Did you happen to order your rad from them? Man I better "L"eave the"M" alone.
I dont see how the notching will hurt (other than to a purist). The only thing out there is the bumper and it also holds your cap up. I would say it "would" make a hit in the side which catches your bumper, possibly bend the frame sideways easier at that point. (but if that happens you will have much worse troubles than straightening the frame)
I would see if I could get a refund before I cut.
If you aren't worried about it being stock consider an aluminum. It will definitely make the 327 happy.
