C A,
I don't think the cam size is the problem, that cam is right about the size I have in my 383 sbc. 282/290 .600/.640 106lca. My motor will idle at 800rpm in gear with no problem if I wanted it to. Does it seem like the lope of a race engine or a constant shake. Could it be the wrong balancer and flexplate/flywheel, internal on external engine?
Curtis