T5 Carb. Which one?!

Hi all

Could someone please help me. I have a 1996 125  T5 Classic  and its running really rich. its stood for pretty much 15yrs and Ive been told a new carb would be in order, as the mixture screw does nothing when its being adjusted

It has a Delorto SI24 24G installed at the minute, but the bike is autolube. All fingers point to an SI24 24E for autolube and SI24 24G as none autolube.

Just for clarity, there is a spearate tank for oil and petrol and they're individually piped into the carb box, there is a geared pump withint he carb box that the oil passes through 

Any help on my choice and why would be really appreciated.