Head gasket what to use to seal gasket

[oldgmc]

I know this has been asked many time but a search of the forum did not give me what I was looking for. I am replacing the head gaskests on my 79 with a 350 I have so far removed the right head the one that was leaking. The directions on the package say steel use a sealer otherwise dry. The gaskets I have are felpro and they have a blue coating on them so I would guess dry but they are the same gaskets that are on now and it failed so I am thinking to seal it to be sure they do not leak and was wondering what to use or is it a bad idea and should I just go the dry route. This is not the origional engine a good wrench engine was installed by the PO. Not sure when but the cylinders are clean smooth and no sign of any wear on the walls so seems to be low milage