The tab is usually correct when it is flat with the float bracket. You seldom need to bend that tab. Did you replace the needle valve? It may have dirt in it or may just need replaced. They do wear out eventually, especially if you leave the petcock open when it's sitting for a long period.
Is fuel coming from the overflow tube?
I'm not specifically familiar with the Mikuni but I would turn off fuel to the carburetors first , then drop the bowls , manually lift the floats to activate the needle valve which would stop fuel flow to the bowl. Then turn the fuel back on. By manually operating the float the adjustment will be removed as the cause of your issue. If fuel continues to flow, your seat or needle is damaged or installed incorrectly. I agree with mleach72 that the tabs usually don't require much if any adjustment. The float tab is a very subtle adj and the fact that both carbs didn't stop the bowls from overflowing may indicate they were the incorrect parts or were installed incorrectly.
Good you got it figured out! This is just my personal opinion, but if you are running dual 45's on a 1200cc engine, that is way too much carb. A single 42 can easily handle an engine up to around 100 ci. That would give you much better throttle response and torque, and probably much better fuel mileage.