small block balancer issues

help a friend out 63 barracuda had a shop put motor in they had no idea what they were doing. after 2 years he pulled car out Im helping him get it running it has a 340 never started with edelbrock heads rpm intake and holley
went to put torque conv bolts in and found out motor would barely turn over with a breaker bar. found the balancer was hitting timing cover pointer for timing mark and bottom of water pump. its def a 340 motor is there diff balancers for small blocks?
i looked on mancini and summit and jegs and looks like 7 in or 7 1 /4 is there also a 6.5 in balancer?
Author: mez