Gas and oil additives

No do not use any additives the unleaded gas will eventually take out your valve seats but if you do not drive it much it may take a few years. When it does then you just get a valve job done with powdered metal seats. Also, replace your fuel lines, the rubber part and if your carburetor screws up get a kit with Vylatel accelerator pump and parts. Or a rebuilt carburetor which should already have that stuff in it. That is for the alcohol in the fuel.

Use a good oil made for flat tappet cams. Most of the oils sold these days will eat a flat tappet cam quick, especially if you have higher pressure valve springs and a good cam.
Don not run most common synthetic oils either. They are better in some respects, but because they are also more "slippery" than conventional oil they can actually cause the lifters to stop rotating in the bore because of the reduced friction at the lifter/cam interface area. That spells an early replacement for both parts.
Google flat tappet oils and you should get a few lists of the current oils that are usable. I run Amsoil in my solid lifter cars and have not had an issue with lobe were.