Assuming the cam & ignition timing to be correctly set - if you're getting a spark at the coil, and not at the plugs - the problem is going to be one of the following ...
a) the lead between the coil & the distributor cap (spark not reaching the distributor)
b) the distributor cap (spark reaching the distributor, but not reaching the rotor)
c) the rotor (spark reaching the rotor but not being "distributed" to the plug leads terminals)
d) the distributor cap (spark being "distributed" to the terminals but not reaching the plug leads)
e) the plug leads, spark leaving the distributor but not reaching the plugs)