I moved mine forward 1 inch, I left the motor in the stock location, and I ended up using the 63-66 OG motor mounts and towers- they only use 1 bolt on the bottom and it lined up w/ the Xmember.
I looked into using the later style mounts but I would have had to fab a mounting plate for the lower bolts.
I also needed to raise my motor up (motor mounts) 1/2 to 3/4 inch to clear the steering which I raised with the Xmember section.
I sectioned the Xmember 2 inches.
this thread-page 11 post 253 for pics:
http://67-72chevytrucks.com/vboard/s...646830&page=11