The manifold will be a simple task now with twin triples
Have looked at the porker race types and will model some up when I get all the bits together to measure .Take the fitment from both carbs and old Atmo manifold unit and blend a form between them .Will have to read up a bit on the shape/distancing to get them flowed properly ,can't have them to near the heads and they will have to curve thro 45 degrees smoothly .
Could do with some piccies of your set-up for a guide please