Easiest way is to grab one from the injected sierras, your ecu will control the spark. You want the one without the vac module. There are usually plenty on Ebay UK. Here is an example, currently at 5 pounds.
http://cgi.ebay.co.uk/FORD-PINTO-EFI-ENGINE-DISTRIBUTOR_W0QQitemZ140395993844QQcmdZViewItemQQptZUK_CarsParts_Vehicles_CarParts_SM?hash=item20b040daf4
Just search for sierra or pinto distributor, you should be able to find what you want.
Shaun