I wouldn't attempt to use a torque converter unless you also use a functional transmission attached. You can use the converter front cover and ring gear with the guts removed with a bellhousing , auto trans case,or a fabricated starter mount if you like .
Correct, if you use a convertor that has the guts in it, the internals will wobble around and cause an out of balance condition. I've used a 130 tooth flywheel with my 727 bell and it works just fine so I don't see why a convertor wouldn't work with a manual bell. This 340 is running in this pic, 130 tooth flywheel with a cut off 727 bell. A 143 tooth flywheel won't fit in a 727 bell.