Jeff, I would say if you are going to jump in do it with both feet. After you have the fuel side going you are more than likely going to want to go ahead and to the ignition. The price of a custom 12 plug dizzy setup is the same and/or more than the electronic setup depending on how many parts you have to start with.
FWIW I am using 6 bosch coils that fire 2 plugs apiece. On top of this I am utilizing 6 Bosch ingitor control modules which allow me to control each spark plug individually hence no waste fire spark or batch firing. I am also going with the smaller 12mm plug on the exhaust side for two reasons, less material loss in the head for a lower compression loss hit and
AFAIK all the older twin plug porsche motors were setup this way.
Charles, I got your cylinders in the mail this week, awesome stuff!! When you setup the efi did you think of using Alpha-N mode for the idle? I know ITB's give false vacuum readings and I have seen a few ways to overcome this. One is to draw vacuum from each intake runer and feed that into a small plenum which then feeds one sensor giving a "whole" reading from all 6 intakes. The other way is in the programming and how I intend to setup the ecu. At startup, idle and low rpms the engine will run in Alpha-N mode in order to keep a smooth idle and constant start up. Then at a predetermined rpm or load point the ecu will switch over to the more common density based mapping once the intake tract airflow has smoothed itself out and does not give false readings.
This all seems so simple now and I am sure once I have everything wired up I will be scratching my head more than a few times but I cant wait.