carb problems.

Hi, Just bought a mk1 with the Weber carb conversion, and its running too rich and not happy starting, and performance not too sharp.
As of yet I haven't dismantled it, but is it right that this carb should have' Kit 15290992' for it to work with the 1.3 engine? If so, are these kits available anywhere?? I think the present carb may be set up for a different engine.
Any tips on set-up and what to check?
Thanks.
Marcus.