Don't over think the situation,start with the obivious things that can cause the problem.
a.check all carb areas for vacume leaks and mixture settings.
b.check intake for the same(tighten by hand,side to side and repeat till the bolts refuse to turn) use a small 1/4 ratch and socket.
c.Check all electrical for voltage and strong spark and firing order.
d.Check distributer for solid timing results.Set timing at 35* at 3000 RPM and no fluctuation at lower RPMs.
e.Check valve settings
f.If everything checks out,look to cam timing.
We have seen bad fuel cause issues also.Cam design,cam timing,distributer timing,valve timing and compression can all effect engine vacume.If you can idle the engine at low RPMs then it is usually not a vacume leak unless the intake is pulling air from the crankcase and then you should see oil foul and smoke.If it shuts off at low idle the leak is above the manifold(carbs).Occasionally if you have a leak and adjust the blades open too far and uncover the idle slots the engine will siphon from the main jet wells and cause an overrich condition.