Hi Alex,
Before you embark on an ambitious exercise, you should go to the museum just outside Port en Bessin in Normandy. There are tanks and other artifacts recovered from the sea around the D-Day beaches. By this time the corrosion is set in deep and I doubt whether you could do anything with them, save for treating them with a stabiliser such as Fertan and putting thm on static display. The museum exhibits have been treated, the product name was displayed, but I forget it now. Strangely, anything rubber is near perfect, all the lettering on bogie wheels just like new.