Run what you got, says the eternal change man (looking at himself in the mirror). Get a packard shutter if you like the lens you have. If you google Kodak 2D Packard shutter and look at the photos, you'll see a few variations on how to get it working.

If you feel you need to change the lot, then go for a lens in a shutter. Just remember the 5.6 lenses are huge hulking beasts if you are hiking and moving the gear around.