It became pretty obvious that my earlier plan to use the original crossmember brackets in conjunction with modified M series engine mounts wasn't going to work. So it was decided to take a different approach - use the alloy engine mounts that came with the 2JZ, and modify the crossmember brackets to suit.
To start with, we removed the brackets from the MA61 crossmember. After a few hours and several cutting wheels, we had a bare crossmember.
Next, a friend of mine (Pete) came around with a bare 1JZ block he happened to have lying around. The plan was to bolt the block to my auto transmission, position it where we want the engine to go, and fabricate the brackets underneath it. It worked quite well!
Note that we used 80-series Landcruiser diesel rubber blocks, which are a sturdy design with studs sufficiently long to go through the alloy 2JZ mounts and still expose enough thread for the nut on the end.
Finally, the crossmember was pulled out for final welding and painting. Top work Pete, it looks great! :-)