I made a plate that picks up on the exhaust flange bolts, but it is made to fit one side only and uses all 6 bolts. I was worrying about it when I did use it on the other side and could only put 4 bolts in.
I see that the original Ford (KRW) stands use the exhaust bolts and only 4 of em so I suppose that's the way to go.
People have reported problems with hanging off the bell, no-one has reported problems with using 4 exhaust bolts and that is what Ford used, so that's good enough for me.
If you hang it off the bell and want to spin it upside down, how can you do that with a wooden prop at the front? It may be all right for one that is just on display, but for building up or tearing down it just won't work, unless the rear mount has a matching front mount that can pivot on exactly the same centres, and then it would have to be a well engineered piece to avoid getting in the way of fitting the cam or other parts.
Hanging off the exhausts is just so much easier, and a proven method.
Mart.