Some questions....

The converter bolts are probably 7/16" then you'll need a new flex plate. Just went thru it with my ATI converter.

I use an old driveshaft yoke, and slide it into the tailshaft, and use some zip ties to hold it in. The only fluid I had leak was from where the lines were taken off. Easy fix there would be to cap them with a rubber hose and a bolt in thend of the hose, slipped over the fitting.