help 1964 Slant 6 tune ups specs

I have everything in place to do my valve adjustment in the morning. Now, this engine is pretty tight with only 1000 miles. I have looked over the procedure several times, and I am very confident that it will go well. If I have time, I will adjust the air fuel mixture, curb idle, high idle, and maybe the timing. I am seeing 2.5 degrees after top dead center on one site I visited. And, I have heard I can go maybe 3 degrees beyond that? I am a rusty old mechanic since I do not do this for a living, but I am seeing the gauge with zero in the center and plus or minus five. I am guessing to the right would be advancing the timing and to the left would be retarding the timing, just like a number line?