Dimensions are 12.7 or 12.8 mm (it does not appear to be completely round ), and 7 mm venturi.

Justengines has the following carbs:
JEN ‘TN’ Carbs
(7.5mm) twin needle
13mm fitting £15
13.95mm - (MDS) £17.50
14mm, 15mm, or 16mm £17.95

MVVS Carbs 7mm for .21-.53
8mm for .45-.61 (or high rpm .21-.53)
13mm fitting £17
13.95 (MDS) £19.50
14, 15 or 16mm £19.95

'Series 3' Carbs 7.5mm venturi - for .40-.53
13mm fitting £15
13.95mm - (MDS) £17.50
14mm, 15mm, or 16mm £17.95

Anyone have a particular throught on those? ( and I do not want to spark a war here....)

Thanks

Frank