Scirocco Register

Does anyone know the size of a sparkplug for a scirocco gt2 91 ex carb engine , I need a helicoil kit for a threaded sparkplug socket , The chap on ebay who sell's the kit's is not sure of the size and say's he think's (M14 1.25) can anyone confirm this , As the kit cost's 50 quid and i want to make sure before i order.
Any help would be appreciated.
Thank's Tom

Fixed now!! The size is 14mm i found out, used a 14 mm thread chaser as advised problem solved.