To start with I re installed my bare 351C block and ZF. I had to do some repair to the ZF mounts and it is covered in the ZF forum here.
http://pantera.infopop.cc/eve/forums/a/tpc/f/9550045562/m/6730095465
After that I tightened down the factory mounts and built a jig that mounted on the front of the block and located its height as well as centering it. It is made out of a couple of pieces of angle and some square tubing. The front of the block is the same between the 351C and 400 in this regard. Here is the jig mounted on the front of the 351C block.
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