critical Clearances 
these clearances  were obtained with engine sitting in frame 
1/2" forward of  original  engine position  measured from  block / bell housing joint
offset in mounting bracket from four mounts that hold bracket to engine is 9/16" down ( ie engine lifted up )
measured  form center line of top two mounting holes 
I will post a drawing soon.
bracket made from 5/8" material  using an Mackay mounts part no. A1128
Note i found that the Mackay mount measures  close to 1 1/8" think  where the US mounts I have measure 3/4" thick
the engine could be set up lower in the frame
but where I have this now the oil pan of the 4L60E is at the same level got ground clearance as the oil pan for a  BB engine 

clearance full  right hand steer

clearance full Left hand steer 

 clearance  alternator to engine mount 

clearance  under mounting

transmission / chassis