POS,
I used the cat gear drive and the tooth part of the gear is about the same thickness but the center hub part of the cam gear is thicker for sure. There is NOT enough room to run the fuel pump eccentric to run a mechanical fuel pump. You will need to run an electric set up. The front cover needs to be clearances along with the plate to clear the cover. 1 hole will also need to be drilled and tapped into the block.
I posted all of the issues with installing one on the 318/402............with pictures!
http://www.forabodiesonly.com/mopar/showthread.php?t=84064&highlight=cat+gear+drive