Very good advices, GAZ. Maybe I can set the floats on the LH side somewhat lower to overcome the problem. Tllting is possible, but alot of work...
Since my fuel- lines are figured as a T (ending at the front of each carb bank) I think that if the problem lie in the lines and the amount of fuel in the two banks, a connection at the front might do some good as well.
I looked at the Redline Weber webshop and I found the largest needle & jet for the 48 IDF available was the 200... (Although in my not- updated catalogue they are listed up to 250, as you mention, GAZ.)
Here we have a picture showing the plugs (4LH/ 4 RH). Quite consistent, or what?