Found a 1930 Sport Coupe, please help me get it running better

[Baumi]

Hi Barners!
I got a 30 sport coupe and I am really stoked because I always wanted one . It has been in the same family since 1965, but the last owner died 7 years ago, so it has been sitting since 05. I charged the battery and got it running, flushed the tank, cleaned everything fuelwise and checked the ignition but it still runs really rough under load. Distributor, wires, plugs, coil and everything else ignition related is and looks clean and new, and every cylinder does have a regular spark. Compression is even on all four cylinders and I cleaned the carb.Yes the carb could use a rebuild in the near future, but the float level is set and all is clean and sealed, so it should at least run better than it does right now.

As soon as the engine is under load different cylinders start to miss,max speed is like 35-40mph, it bogs and rattles like there´s no tomorrow. The battery is charged and the voltmeter shows 6.25 V, with the engine running @ idle the voltage drops to 6.02V. The car has been converted to a modern distributror and an 6V alternator. I would rather have it stock but for now I would like to use what I have...
I will attach some pics, I hope you guys have an idea what I can try next
Thanks Chris