I know nothing about a grinding attachment, I suspect you might have checked lathes.co.uk
I have a 2B but I’m unclear whether you are asking whether I know about the existence of a vertical head or the existence of a vertical head for sale.
The same aforementioned web site will tell you that two types of vertical head exist, a knuckle head and the much more desirable quill head. There are also horizontal milling attachments, which you may have, an overarm, bracket, arbor etc. The Centecs are very nice British made machines but probably went out of production in the late 60’s. I regard mine as a medium sized gem and is most definitely not for sale!