A 26mm AND a 27 mm choke size, although the person above ran 40mm he maybe did not get to the limit of them.
I can ask me mate who is very versed with tb's if you like, but another that springs to mind is Dave College of Retroford, he had a super quick escort estate making around 280 on 40's(Ithink), was ok till a fuel hose split!!, went onto to do some bloody good times.
tabetha