hi mate

if you are certain there is power to the coil when the key is at the ON posistion and the starter is cranking there is only one other posability for having no spark and that is dizzy,

just an idea

first to check wiring to coil,

take off both wires connecting the coil and turn the key to the ON posistion check which wire is POWER+ with a test light, connect it to the + side of the coil

now to test your distributor wiring ( i havent tried this method but in theory it should work )

the one other wire to coil that isnt power, connect this to a test light, and the other terminal of the test light to battery + now crank the engine, if the test light is always on something in your distributor is causing the coil to always be earthed.
if the test light is always off then your coil is never earthing and wont charge to be able to spark,

like someone else suggested you could also check both at the same time by running a test light across + and - on the coil and checking for a flash while cranking

if the light is flashing as you crank it is possable your timing is incorrect,

hopefuly you can make some sense out of this