Is the lower timing gear on a 1.6 8v the same as what's on the 1.6 16v? Think that's my problem!

It might depend on where you are and what the engine came out of, but, if I assume US, then no, the gears are not the same.

Some, but not all 16v engines have a crank position sensor that detects a toothed wheel on the crank pulley as far as I know, none of the 8v engines have this sensor.

Is the lower timing gear on a 1.6 8v the same as what's on the 1.6 16v? Think that's my problem!

No.  The 16V gear is wider, because it uses a wider timing belt.  The ODB2 (96 and later) 16Vs also have a crank sensor, so they use a different gear than the earlier 16Vs.  So the later 16V gear will work on an earlier 16V, but the earlier gear won't work on a later 16V.