Converter problem?

First question I have is why do you have a stock 360 ideling at 780 rpm? That's where my built lumpy cammed 360 idles. Should idle at no more 750 rpm max in neutral. How's the tune up? Could be just the carb out of tune causing it to drop so much. I haven't seen a converter do that. Not saying it can't. Just ain't seen one do it.