I've built similar motors that made above 6000 HP after sorting out the aftermarket carbs. All the ones I built and dyno tested for customers that had the original street hemi carbs with similar parts all made above 600 HP with stock jetting
Is your intake manifold stock? If so make sure and replace the right rear secondary jet(rear carb) with a .075 I.D or smaller tp start with, do NOT leave the stock jet in that carb It will flood #8 cylinder, those intakes had similar jetting on all the stock street hemi carbs from the factory 1966 to 1971, they had either .065 or .063 in them stock