I concur, get the largest one available that will fit the lensboard. Get some material to act as "stand-offs" and mount the packard shutter to the lensboard. The lens is attached to the lensboard via a threaded mount. You will need some sort of hole for the mechanism on the Packard shutter to stick through the lensboard. This is allows for the rubber tubing and squeeze bulb to be mounted and you will need this to be able to "fire" the shutter. I know several people that made mounts for the front of the lens and while it looks sorta "yucky", it works just fine.

lee\c