Initial timing=8 degrees
Mechanical advance in distributor=26 degrees (at the crank)
This may be a little high for todays gas. I would limit total around 45 degrees.
Here is a method for finding the optimum timing settings. It is best if done on a hot day.
Disconnect the vacuum advance hose and plug it.
Set the initial timing at 8 degrees.
Take off from a dead stop and see if the engine pings right off idle. If it does, then back off the initial timing until it stops.
Make sure that the mechanical advance is correct with the timing light. Then take the warmed up engine out on the road and floor it.
If it is an automatic and it pings just after it shifts into a higher gear, back off the mechanical timing (you may have to buy a spring and weight kit).
If it is a stick, put it in a high gear (like 3rd) and floor it. If it pings, reduce the mechanical advance in the distributor (again, you may need a kit).
If it doesn't ping, then put the vacuum line back on and drive it up a long hill. If it pings, get an adjustable vacuum pot and back off the total available vacuum timing by the screw/cam adjustment on the inside of the distributor (NOT the screw inside the vacuum nipple).
Continue the above steps until you get it to never ping and you're set.