Homemade EFI, what manifold?
Buy a manifold with bosses pre-cast for the injectors. Then simply add a four barrel throttle body and you're nearly there. For example, I believe the Edelbrock Victor series manifold already has the bosses precast.
Someone skilled with a drill press, or a friend with a mill can drill the bosses for your injectors.
For electronics look into Megasquirt.
Regards,
Joe Dokes