I am putting together a multiport system for a 390 shortly, using a Megasquirt controller, DUI HEI distributor, and a 4BBL intake with a throttle body and adaptor from an EFI 460.
Here is a site that tells how to make the fuel rails and intake injector bungs. It deals primarily with using a Subaru engine in an aircraft, but the technology is the same.
http://sdsefi.com/air12.html