[goinbroke2]

Flat lobe on exh would cause popping out carb.

If it's a miss while reving in neutral I would of closed off the choke and check the result.
Also look down the throat while reving and see if it's a smooth pattern of fuel or blobs of fuel from the emulsion tubes on both sides. If it makes no difference, rev it and move the dist around(advance/retard) and listen for a difference.

I'd also close the gap on the plugs to about .030 just to test.

Another dist wired directly to batt and another carb will prove if it's external. Your saying you've switched dist and carb so next is;

Comp check and leak down

Valves are adj right.....you didn't leave the break-in valvesprings on did you???
vacuum leak, p/brake hose cracked or carb gasket etc?


And the "out there ones"
Same oil pan as the dyno? thinking oil pump sucking the pan because of lack of clearance and the resulting vibration/cavitation acting on the dist causing spark scatter.

How did you lift the engine to install it? undo an intake bolt or remove carb and use lift plate? Check those area's for warp/vac leak