The fueling differance between carbs and TB's is:
TB's need fuel fed under (high) pressure,
Carbs need volume of fuel under relativly low pressure.
I bought a cav 16v with teh carb conversion already done. It used a red-top fuel pump (place it as close to tank as poss as they pump not pull), and a pro-line fuel regulator. Both available from demon Tweeks at abot £65 and £20 respectively.
I have a receipt for modification to the pick-up pipe in the fuel tank as well. Not sure what the mod is but I assume it is to try and make sure the fuel pick-up is constant.