Hey Neil, Welcome to GadgetmanLand!
Would be super, Mate, if ya could give us pics of this carb, several from different angles. Definitely shots from underside w/ detail of throttle plates and how much room is under the plates.
Some carbs are do-able, some not. Depending on room under the plates and intruding things like screw holes, etc.
As Dan said, you only Groove the Primary barrels of any 4-bbl.
I've thought of doing a Weber too, if I convert to one for the Subie. Gawd, if I do much more to Subie it might forget it is one...
anyway, Welcome, Neil, have yer roo put another shrimp on the Barbie..Oh I have a real Yank Tank, weighs over 3 tons, old enough to have been married several times...
Tracy G