I’m pretty sure those head gaskets are no longer made. I built a budget 318 from the 80’s a few years ago for my desoto. I had the roller cam reground by bullet cams. The rest of the motor was rebuilt stock with magnum heads drilled for an LA intake. Had a 600 Holley, headers/2.25 dual exhaust. The motor was out of steam by 4500rpms. I just swapped in a lunati voodoo cam and the difference was night and day. I know roller cam prices are far from budget friendly but I wouldn’t advise having one reground and expecting huge gains.