For 4x5 i use a Speed Graphic but only because of the focal plane shutter. It would be nice to use the new lens with the speed graphic, but it's not a must-have.
Maybe i get the 300mm as my first lens...and add another lens later. Or is there any special trick that makes the 360mm special?
For portraits i think would go for half body shots as a maximum...but most of the time i do slightly wider shots..