Picked up new case attachment hardware to use with the new mount:
2x 35mm M10x1.5 bolts
2x M10 washers
1x M10x1.5 nut

As expected, the JB Weld failed right in the middle of the joint once the handle was tightened down. Turns out all my efforts may have been a complete waste... Once installed, the weight of the engine seems to bind the yoke in the socket enough to lock the desired rotation in place.