Hi Nik
I am in the middle of a rolling restoration.
I think all these old car will rust so might as well use it!
I am trying to eliminate all my rust.
I thought my was solid untill I started to remove wings etc.
I don't want to alarm you but some of the chasis rails are real water traps and seem to rust from the inside out.
I just keep finding more and more.
The good news is that I have an expert car restorer doing my car and I help out doing the donkey work to keep costs down.
It seems that almost anything can be mended though.
I don't seriously think you can rust proof these cars unless you really strip the panels off.
Save yer cash use it untill it starts to rot then get the right people to restore or restore it yourself.
Nice car by the way