There are millions of cars on the road that don't use sequential. From what I've read, it provides minimal HP gains, a little better emissions and idle quality.
go over to "Binder Planet" and search up the section on EFI. Guys over there are using GM stuff to convert IHC 4, 6, 8 cyl stuff to tbi, multiport, etc, using re--chipped GM computers. I thought about doing this.
Search up Megasquirt, another DIY possibility.