If you're getting a strong spark from the coil into the center pin on the distributor cap, but no spark at the plugs your problem would have to be in the rotor to cap interface, seems to me. MSD has a bunch of different rotors and caps, so I'd be checking to be sure that I got the right rotor for the distributor & cap, and the right cap for the distributor. Doesn't take much of a mis-match to block the spark, and it's easy for a parts guy to grab the wrong part, especially if it's a kid thinking that all MSD parts are the same.