It fits real tight. Try this, get a bar that is slightly shorter than where the brace goes into. Get a nut and a bolt. Put the nut on the bolt. Put the bolt into the end of the bar. Now stick the bar bolt set up between the mounting points of the brace in such a way that you will still be able to get the brace up there. Use wrenches to back the nut off the bolt which essentially makes your bolt rod combination longer. This will help spread it apart to aid in getting the brace in. Clamping devices and BFH's are also still helpful. You'll probably need two people. Have someone hold the bar with a pipe wrench while you turn the bolt out so it doesn't slide around too much.
Former owner of 94 Bird with DOHC 4.6L swapped from a mark VIII
2011 CTS-V Wagon
1968 Torino was an original 289, C4, fully documented numbers matching car. Now: DOHC 4.6L/T-56 swapped, Cobra intake, IMRC delete, BBK long tubes and H pipe. Dynotech Aluminum Driveshaft, 9" rear with TrueTrac and 4.11's.