Kees - Here is a thread of what and where I notched for the Jag to fit into my frame. About halfway down, he has pictures of the little notch he made to fit it into a 34" frame.
http://www.jalopyjournal.com/forum/t...o-f100.571296/
Here is mine, all welded in. I think I am going to add a few more filler pieces and do some more welding now that I have the frame up in the air.
I hope this info helps. I think it is a better way to go than removing the crossmember and squeezing the frame to make the Jag fit. If you did that, then you would have problems with the radiator support mounts and bumper mounts. It would be hard to get your front sheetmetal aligned if you did that.