<VV> Undercoat interior floor pan?

[Steve Brennan]

I am  in the midst of restoring my 1962 Spyder and have removed the interior and cleaned up the floor pan.  (Nothing more than surface rust, thank God, due to it being an original Southern California car that sat in storage under a carport from 1974 to 2006.)  I wire brushed the rust that was there and then prepped the cleaned up metal with a "rust killer" spray and now need to decide how to surface the floor pan.  Any reason not to use rubberized undercoating?  I was thinking that it would help prevent any water that gets inside from getting to the metal.  BTW, I also intend to put down some rubber foam soundproofing/insulation under the carpet (perhaps instead of the jute if it gets too thick), and I thought that the rubberized undercoating could be helpful if moisture got between the rubber foam soundproofing and the floor pan.  Any thoughts/suggestions/warnings?

Thanks,
Steve Brennan
1962 Spyder Coupe