Should I replace all the fuel tank hoses while I swap the gas tanks? Even if the hoses are still in good shape?

If you are going through the trouble to swap tanks by all means go ahead and change the vent hoses now while you can get to them. Even though they may look oK, when you go to take the tank out you may find they are hard and brittle. It's a lot easier to replace them now than it will be in the future, and it's a little insurance that you will have one problem erased and not have to worry about for years to come.

I agree! There will not be an easier time to change the hoses on the tank than now. You have to drop the tank to change them so why do it twice!? Besides there is a good chance they are 10-30 years old and will probably be damaged when you disconnect them to remove the tank. If they are original type hoses it is difficult to inspect them since they have a cloth braiding on them.

If you don't use factory replacements be sure to use a hose suitable for fuel, NOT heater hose.

Have fun!

So I should replace ALL the rubber hosing just to be safe for the fuel tank? I guess I'll be calling up MSA for new hosing

I guess it depends on your budget and how much you like the smell of gas in your car. I would replace all the rubber ones that go to the tank. The exception would be the large filler neck which should be inspected but may be okay to reuse. If you have the money replace the rest. Down the road you could replace the rest without needing to drop the tank again.

I already suggested if you don't use OEM hoses be sure to use fuel hose as a replacement. I also wanted to mention that if you don't use OEM hoses, with all the bends in them, be sure you don't pinch any of the lines at a corners, where the bends were. With standard fuel line it is easy to pinch one and then the tank will not vent properly. If that happens you may find you cannot get the tank to hold more than 5 gallons or you may create a situation where the fuel pump cannot draw gas out of the tank.

Have fun!