There are 2 aspects to the timing if the head was off. Timing belt timing and ignition timing. If the timing belt is not correct then ignition timing will be off as well. If timing belt was set up correctly and the distributor was not disturbed then ignition timing should be very close.

What timing have you been trying to adjust and is the knock semsor hooked up OK?

To set timing belt correctly and check/set igntion timing should not take more than 1 hr if they know what they are doing.
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David Hunter