I am about to install a 273 into my 65 Dart wagon and I'd like to use the old heat shield gaskets on the exhaust manifolds. They are in very good condition but I am worried that they will not seal properly. This is not a problem that I want to worry about in the tight, early A-body compartment! Should I use gaskets in addition to the shields? Sealer? Or should I omit them entirely? Thanks for any help!