Chris, did you make sure that BOTH the live terminal on the coil, known as the SW connection, AND the red wire from the electronic unit inside the distributor are both now connected to the live feed -that is the white wire on the HB loom? Also that nothing else is connected to the negative side of the coil, the CB terminal as it's sometimes known, except the black wire that comes from the new electronic gizmo.
I found after fitting one of these years back, I had to adjust the static timing a little bit. If you can't rig a test-lamp to determine when the electronic unit cuts the earth connection to the coil, when cylinder 1 is approaching TDC, then try after noting the approximate position of the distributor body, loosening the clamp and rotating the distributor body first one way just a few degrees and if it doesn't start then try turning the distributor body back past where it originally was, till a few degrees past that point in the other direction and trying there, just nip the clamp loosely between trys. If you've a helper, then get them to turn it over on the key while you try turning the distributor body again just a little bit, one way then the other. It might just get it near enough for it to start and run, that you can later obtain a more accurate setting using a strobe light.
I had also done a rough and ready how-to back in 2012, if it's any use, bit wordy, but might help.
viewtopic.php?f=12&t=17620&start=10Also if you've a dynamo/control-unit, rather than alternator, the electronic ignition unit might not like the rather spiky system voltages that can result, as might not some strobe-lights, causing it/them to trigger inappropriately, but it would still run though maybe imperfectly.