Mild 318 pinging

Ok, I have more info. I went ahead and re-checked the entire mechanical advance curve as follows. Initial 10* at 700 with 19" vacuum in park. Drops to 600 in gear at 15.5". 10* at 900, 11* at 1000, 12* at 1200, 15* at 1400, 17* at 1600, 21* at 1800, 23* at 2000, 25* at 2200, 30* at 2400, 32* at 2600 which is full mechanical advance. The vacuum can I am using adds 2* at 7", 8* at 10", 16* at 12", and 20* at anything over 14" and it is hooked to ported vacuum. At 55 mph 2100 rpm I am pulling 16-17" vacuum going up the hill in question and it will start rattling if you don't start letting off the throttle until you crest the hill. Obviously, I am pulling the full 20* of vacuum advance under those conditions so it makes sense that unhooking it got rid of the ping. At 40-50 mph on level road it is pulling 20" and 55-60 on level road it is pulling 17.5". Under what I consider normal acceleration thru the gears, it is pulling 12 - 14" of vacuum which is adding 16 to 20* of timing to the mechanical. I see several options if I am understanding things better now as I think I am, in no particular order.

1. Go back to the factory long loop spring on one of the weights to slow down the higher end of the curve and leave the initial setting and vacuum advance alone. From the info that has been posted, it appears to me that the upper end of my advance curve is too hot for 87 octane and 2.76 gears.

2. Back the initial timing off to about 6* instead of 10* and see if the idle in gear is livable. Leave the vacuum advance as is.

3. Leave the initial at 10* and try to back the vacuum advance can off about 4*. Does the adjustment on the can adjust the total amount of advance or does it just change the point that the advance starts? I'm thinking that it changes the start point.

4. I'm thinking that I probably have too much vacuum to run manifold vacuum on the advance without backing the initial setting off to about 0 and redoing the advance plate to allow 28-30 mechanical.