It depends on several things. Firstly, does the car have auto or manual trans & is the cam, carby & exhaust factory stock or modified.

If it's basically stock, the vacuum advance can have full vacuum at idle if it is an auto, but the vacuum should be 'ported' if it's a manual.

Next is the basic timing, HQ/HJ were set at 6 degrees initial, but this was different for HX/HZ. I've found that if you're using 98 fuel (which you should be BTW) 8 degrees is a good starting point & you can advance or retard from that point by listening for pinging.

If you are running a different cam, carby or exhaust, then a different mechanical (centrifugal) advance curve is required. No amount of changes to initial timing will overcome the problem. With the wrong curve, if you retard the distributor enough to eliminate pinging then you lose power. You can't have both.

Dr Terry