Hi Owen,
Restoring woodies is fairly straight forward. You can use a hand cleaner such as Go-Jo, which is available from about any auto parts house, to clean the wood. If use judiciously, it will clean without taking all the color years of sweat and grime has produced.
You can then use BLO or something like Watco clear to reintroduce moisture into the wood. Just make sure to not have the iron in the plane as any swelling can make a snug wedge very tight. Also, make sure to allow the planes to equalize in moisture content before you oil them up, and before flattening the soles.
If one is a smoother sized plane and the mouth is open further than is applicable, you can let in a mouth piece to close the mouth up a bit. This is a very period appropriate method of repairing the front of the mouth. Planes longer than 14" don't need a tight mouth.
So a little cleaning and flattening, cleaning the iron, oiling the plane will make them good usable planes.
Take care, Mike