It’s been a few weeks now and quite a lot of miles since I swopped the carbs over and reset the mixture etc. So a good time to see what the spark plugs look like as a good indication whether the carb settings are correct.
I found this excellent chart on the internet with a good explanation what it all means
I reckon the plugs above look pretty good. If anything it may be slightly on the rich side so I tweaked the mixture on each carb by quarter turn.
Another thing to note is that the workshop manual states that the spark plug gap on rubber bumper MGBs fitted with the 45D4 distributor is 35thou not the usual 25thou!
Will check again in a few weeks.