Fitted the new Mikuni’s- all very good, cured ‘vacuuming’ until i get a bit brave and get between 5-6krpm and the aproaching sweet spot disappears and the power drops. From my little carb/breathing knowledge and more realistically from my mechanic, I get the impression that raising the needles a notch or two would be the next area of investigation before looking at the jets.
My mechanic had broken the old 'vacuuming 'carb I had given him for ultrasonic cleaning and a service. Trying to remove the seized mixture screw cracked the carb casing after heat and all manner of persuasion 
Still solved the problem there and he sourced theses TDM/ TRX new 38mm Mikuni’s. They were advertised on eBay as also fit’s for SS among others, sold by DC Motorcycles in Kent 
No adjustment was noted in the add so I fitted with the above result so for the needles I will go, but before that I wondered if I should go straight to the Dynojet stage two kit? not sure about the old carbs tune but the bike has a K&N air filter a very modified air box cover and very loud ( so I’m guessing modified internally, de-wadded if that’s possible) standard exhaust
Also attached is the old carb damage just to illustrate.