To use the 790 with the current Power Bloc clutch I needed to space it out to accept the wider belt, I got lucky when I was in Florida a friend call and said he was selling his house and needed a place to store some of his shop equipment some of that equipment included a lathe :-) The challenger came with a series 500 driven clutch using a 15/16 wide belt and the belt Bill gave me with the 790 driven uses a 1.250 wide belt.I made a spacer that will sit under the spring and provide enough width to accommodate the wider belt, doing this will actually compress the spring if you do not make a equal spacer to use under the cover, now the center bolt that threads into the crankshaft will have less thread engagement than before, I got lucky and had a longer bolt that came off a junk Power Bloc that used to be installed on a FL350, it was about 1/4" longer than needed but the length did not need adjusted because there was enough thread depth i the FL250 crankshaft.
Here is the belt that will be run with the 790 drive clutch, it looks like I have enough side clearance for the belt for when the engine is just idling.
Working on it check back later 1-1-02