Thankyou for your help chombi that has made things alot clearer.
I do have one more question though as im still quite new to the classic bike era, what is the difference between campag and shimano downtube shifter mounts, as in is ther any difference in shape of the lugs brazed onto the frame? As im trying to work out which sort i have on this frame, the source of my confusion is that the majority of the brazed on mounts ive seen are circular with two flats either side allowing the shifters to slide & screw on. However the downtube mounts on my frame (as shown in the OP) are completely circular?
Also in a moment of weakness/lack of experience (oooh.... shiney things) I did buy a pair of Shimano 600 ab levers without thinking, assuming it would just be a case of using a spacer to take it off the band on mount and mount it directly to the frame, can I still do this?
Unfortunately, I never owned a bike with Shimano specific shifter DT shifter mounts on it, but IIRC, there is a difference with the Shimano mounts that do not let their shifters work with other mounts unless they are specifically designed to do so (My Vitus Carbone with "regular" non-Shimano proprietary bosses had DA 7400 shifters on it originally.) Not sure exactly what the difference is, but it might be the diameter of the mounting shaft and/or/maybe the threading of the shifter mounting bolt. Somebidy here must know and can clarify that for you.
Chombi