Hi, this may be a dumb question, BUT... I have a '68 Stang front clip (front seats forward) on my '67 coupe. The clip is from a CA car and appears very solid, only rust is at battery box and the spot weld cluster, center/top of passenger inner fender.

My question is; what can I do to the front torque boxes, frame rails, and rockers (INSIDE) to stop any rust that may be there and prevent new rust? I know I could open these areas up but I would like to avoid cutting up the whole structure that is solid at this point.

Anyone dealt with this type of issue? Thanks for any advice.