If you left the dizzy on then did you get it skimmed?
Have you checked to make sure you have sparks and fuel?

Having left this for a while due to other projects I'm still having trouble starting as before, fuel, spark and the engine turns over but won't fire, yes the timing is correct.
Any help appreciated.

is the engine turning over fast or slow i.e check out earth . cheers ;)

I think it's a bad earth but I'm buggered if I can find it.

i wound go with coil earth first and back track .;) keep on it . cheers.

fuel
spark
compression
cam timing
ign timing

work through the list.