Just got my first slant six

I just picked up a 73 Dart Swinger with a slant six. I noticed the garage floor where it had been parked was black under the tailpipe. I jump started it and drove it home over an hour and it ran fine and didn’t smoke. The oil light flickered at stops and sometimes stayed on. The engine and compartment are covered in what looks like a few years worth of oil. I checked the oil pressure with a mechanical gauge and it idled around 5psi. I checked compression in the cylinders and they were 70, 80, 75, 75, 75, 80. It has electronic ignition. The plugs were all gapped around .040. They were covered in light brown deposits and one of the insulators around the electrode was gone. I’m hoping to flip the car but it could be a keeper too. I have to replace the engine mounts and tranny mount.

My mechanical skills are low but I’ve been learning a lot from you guys and my friend who is a mechanic. With that info, what are your thoughts for the least intrusive and most economical steps to take next?