I have a 1300 crossflow with an A6 cam fitted, it has had some head work.
Will be fitting twin 40's.

Anyone know what the jets, emulsions,chokes etc would need to be?

Take a look at the following link for a good baseline set up.

WEBER JETTING LINKY

will take a look thanks

If you go to the 9th item in the 1st download list here linky there is a program to give you all the info you need.
Cheers,
Bob

Also you could contact Burton Engineering, they are one of the foremost x flow engine experts in the country and will sell you just about everything you need and give advice.

Fast Road cars are also a good contact they are on the net a really decent bloke knows his stuff about webbers and supplies jets