Bought a 51, got questions

[vht]

Went and looked at it today and bought the truck. Have to pick it all up this weekend. The cab has heavy surface rust on it from being blasted and then stored in a unheated pole barn. It is a stripped cab, so the rust is inside and out. Don't really want to blast it again, so is the anything I can use on it to neutralize the rust? I can DA the outside and some of the inside, but there will be a lot of places I can't get too. What would you all do in a case like this? I'm sure I'm going to have more questions. Need to get all this stuff home and take inventory. Love this site.