Miss-fireing V8

Can anyone help, i have a 3.5 su carbed v8 with electronic module ignition, i think its DU35 lucas. Starts and ticks over lovely and drives but underload looses power and mis-fires badly. I have replaced and balanced carbs, fitted new plugs, leads, cap, rotar, coil, inlet manifold gasket, fuel pump/ filter and ignition module, and still has same problem. Thinking of changing dizzy, any advice as its costing me a fortune.?

I need the same assistance on my v8, changed plugs, leads, points, coil, set gap, got it idling beautifully, but alas, as soon as it's in gear and I try go up even a small incline, misfiring and backfiring to no end.....