None of them are worth preserving. As long as you are having fun, just put in as much effort as you see fit.
With a view to make them usable, just get them clean so rust and dirt does not transfer to your work. You may also find the standard irons are just fine, especially if you plan to use normal timber.
If you add up your time spent restoring them, along with the sundries required it may be more logical to buy new. However I find bringing life back to an old tool an enjoyable distraction. This recent saw cost me £1 and took one hour to sort out.