HI Louis!
I would not think twice about the difference. What I believe is aggravating is that a friend wanted to use G6 wheels on his 2001 GTP. The GTP has our familiar 115mm bolt circle. The G6 has a 110mm bolt circle. No dice is what I told him. I also believe that your hoax is correct.
I had a 72 Cadillac Eldoradowith te 501 C.I. engine. The same piston for the
455 olds was a lot less than for the caddy. Have a great Christmas.