Which intake manifold

you could go all european and fit a 38x38 weber DGAS
usually used on 3-3.5 liter ford v6...

there is an adapter used to convert 80s jeep carter BBD manifolds to one of them...presume thats for the 4 litre jeep engine
its not going to be a common set up in the USA as i don't think ford Europe sold many V6 (Europeran Capri like atme ford mustang) Ford capi GTs in the US although they did sell some.

the beatuy of the weber is the setup is all bolt in
the pain of a weber is its far to customisable to just bolt on and go..

36x36 DCD might also be fun....
but then again 3 2 inch SUs or indeed 3 dcoe 40s with 34 mm chokes would turn a torquey motor into a torque monster ideal for ploughing fields or pulling a boat full of bilge up a slip