[taff2]

Sorry Tom s - '59 to '60 389 has 3" mains, both of ours are a '59 389.
Tom v, thanks again for the info, just to clarify - my intake will have the injectors fitted in a pair of 2" plastic carb spacers under the plenum box, placed at an approx. 30 degree angle and firing directly down the opposite port into the Offy plenums, 4 injectors per plenum. Here is a (very) rough sketch of what it will look like- what's your opinion on this? Thanks.
And a pic of my modded Offy intake plenums.