Ok, once I’d attached the inlet manifolds, carbs, carb to airbox mainfold it soon became apparent that the carb to airbox mainolf had shrunk as it didn’t reach the airbox by about 5mm. Turns out this is fairly common, I’m guessing the manifold rubber isn’t UV stable?
So that left me with a problem of how to bridge the gap. You can’t move the airbox forward without modifying the frame brackets and slotting bolt holes, which I didn’t want to do. So I used some scrap 5mm aluminium plate, drilled two holes and bolted the manifold to it and then then cut and filed it to shape. All that time as an apprentice filing rough blocks of metal until they were parallel within thousands of an inch finally paid off.
Result was manifold now reaches and seals the airbox, BOOM!
Had to increase the amount of filter adapter sticking out to 15mm and tightening the jubilee clip on the filter was a nightmare as its under the subrame cross brace.