Pete with that twin port head of yours you could go crazy!
they also did a twin carb kit with 2x 10tt9's
however more seriously given you have an 1 3/16 which will work fine, you may find you can do a trade as the bigger sizes are more sought after in general. Beint the UK you probably have more options for swappsies.
for the road one carbs better although the bragging rights for twin carbs might be worth the hassle. it was a factory option!
cheers
Tim