I bought one of these off Ebay a year ago and it's been great!
http://www.ebay.co.uk/itm/Electronic-Ignition-Bosch-JF4-Distributors-no-Vacuum-/390220913486?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item5adafa9b4e" onclick="window.open(this.href);return false;