I'd start off by calling Stan at Ford Powertrain Applications (
http://www.fordpowertrain.com)
They don't seem to catalog anything directly for the 289/Galaxie combo but I'd expect there's enough room for various possible shorty-header combinations. Probably not the Mustang Tri-Ys, I suspect those go the wrong way.
I'd avoid long four-tubes, on the street they're usually a horrible ground-clearance problem, especially with power steering.