You have EMPI 47 - 7411 duel 34mm Carbs , ( Look at your second photo and above the screw on the right side of the carb, it is stamped EMPI ) When gone through and set up correctly these carbs are decent on a mid cc engine as you have . However, they need a fuel pressure of no more than......... 1.5 lbs .....to function correctly. When I buy these carbs the first thing I do as I did with yours, is to disassemble each carb, check for manufacturing debris and confirm nothing is blocking passages etc. Then set the floats (they are never correct from the Mfg. ) Lastly I pre-set the butterfly so that both carbs have the exact base line sync , I then run both carb's idle screws in exactly 2 turns which still keeps the carbs mechanically synced. This is a start up point that allows the engine to run while making additional mixture and idle speed adjustments. Constantly changing out two fouled plugs then restarting you engine will quickly "gas wash" the two cylinder walls that are getting unrestricted gas flow and dilute your crank case oil which will destroy the, rings, guides, main and rod bearings hence, you may soon be looking at a full engine rebuild. ( Check compression now see John Muir's book for the correct procedure) ) As mentioned, all you need to do is add in a quality in line fuel pressure regulator and set the fuel pressure up with a quality and accurate fuel pressure gauge. I am 90% sure that your " gas leak " when the car is parked with the engine facing down hill from the fuel tank is a carb needle to seat issue ( excessive fuel pressure) which is allowing unrestricted fuel flow. This is "basic mechanic's 101" aka lawn mower knowledge, perhaps you may want to consider locating another mechanic. Hope this information guides you .
This is your duel carb kit: