Thanks mattalac. Plenty of people have shortened the shifter before, but they usually didn't have to move it quite that far. The better way would have been to weld the box to a mount. I don't have a machine that will weld aluminum, so I went this way.
After about five days of work I finally have the frame modifications finished to make the engine fit in there the way I want it to. It took a while as the mods were more extensive than I thought they would be at first.
You can see the original frame in the original crossmember picture above. (as usual I forgot to take a before picture)
modified:
Frame mods 1 by
Kevin Frank, on Flickr
frame mods 2 by
Kevin Frank, on Flickr
The rotary is a lot wider at the bottom and made it necessary to widen the rails to set it down low. All the other threads I've seen on this set the engine above the frame rails, with attendant problems of the oil pan rails occasionally hitting. Not to mention what it does to the center of gravity.
I welded in two 1/2 thick plates to the outside of each rail between the body tub and the suspension points. Excessive, but it covered the existing flange on the bottom of the rail perfectly. I then trimmed one inch from the inside of each rail and welded 1/8th inch plate to close off the inside. I had to notch the driver's side rail another inch or so for the oil cooler line and the oil bypass sticking out the side of the bottom middle iron. This ended up being the entire width of the rail except for the outer layer. The front crossmember had to be further trimmed to give me enough room to push the engine a little further forward. After taking part of it off I closed it in with more 1/8th inch plate. I then welded in 8 studs and crush tubes along the sides and front for a skid plate/ frame stiffener. It will bolt underneath to tie the entire front suspension together. It will be considerably stronger and stiffer than the original.
Most people don't go this far for the swap, but I'm kind of anal about chassis stiffness and a low center of gravity.