Are you still running the standerd dizzy if so check the faze censer and it's gap . Next wot I would do is pull all the plugs out and if you have any new ones put them on the ht leads and put them on top of the rocker cover .
Then check the crank censer is clean no oil on it and the gap is right . I would think of the top of my head it will be one of these witch is the problem if not reply and we will have to look deeper into it it's a big help if you have a mate with a Cosworth that you can swop bits to find the problem but remember your running wasted spark from the way I'v read it so don't plug a none wasted spark ECU in as it will kill the ECU . All the best keep me up to speed