318 Won't Start? And I tested as much as I could I think?

Look QUIT fiddling with the carb/ gas/ tank/ worrying. I've fired up old engines with NO carb just an open manifold. Once you determine you have COMPRESSION, and convince yourself that the CAM TIMING has not slipped, and set the IGNITION TIMING, and if the plugs/ wires/ cap / rotor etc are in good shape (and firing order!!!)

You should be able to squirt between a teaspoon and tablespoon of CLEAN FRESH fuel (gasoline) down the carb throat and it should FIRE

it may not run long, but it should "hit" for 1-3 seconds or so, enough to let you know "this can run"

Did you read my thread test firing that magnum? That thing did not crank 3 seconds and it FIRED

And stop worrying about "what octane" and just get some fresh fuel. FRESH