Same
problem on one I had, I can tell you exactly what it is.
The first thing is there are three cambelt pulleys that need to be lined up, not the usual two as on the 16vs. Crank and Cam Pulley and then one drives the distributor, this pulley has a dot mark on it which needs to be lined up to the mark on the top of the crank pulley.
If thats okay, the dizzy has to be seated correctly as follows;
With the engine spot on TDC;
The distributor has to be fitted so that the rotor arm points towards the notch on the distributor body, BUT, the distributor shaft has a notch on the bottom which mates with the drive tongue for the oil pump, this is the important bit, and is tricky, that drive tongue has to point to the hole for the clamp bolt.
ie
ENGINE
\ drive tongue
.O clamp hole
FRONT OF CAR
Ie you would have to remove the distributor and fit as above, takes a few attempts believe me!.
To save cost, I would set at TDC first and try fitting the distributor as above. As the other check recquires removing the plastic and an outer pulley to see the timing marks.