Hard to visualize, but I think you gain the standoff plus half the thickness of the marcel and hub flange. I don't have a good feeling about refastening the plate with anything other than hrdaulically-stamped steel rivets (i.e. what's in there now), so I still think you are looking at an outsource job and not a DIY.

It is a small gain, but is it enough so that you only need to shave the backside of the bellhousing (which IIRC is thicker)? It only works if it all fits inside the bellhousing, as well...

Randii