Thanks for the quick response(s).
AFAIK, the 840 heads are essentially the same as the 391's...both square port closed chamber heads with 2.19/1.72 valves. I *think* the only significant differences have to do with which heads are drilled for temp senders, but I'm not 100% sure on that.
Just considering the cost of the 391's since they're so rare. Then to tweak them for performance use essentially destroys the re-sale value. Same thing goes for the 163 intake vs. the 069.
The carb size is no big deal. 780 cfm is plenty once the fuel curve is right.
Just kicking around some ideas right now, wondering what the options were.
Much obliged gentlemen.
Eric