I do know that the location of the oxygen sensor is important. It typically needs to be installed in the header collector at 3 o'clock, 9 o'clock or higher. Below that it will foul.
I have always been advised that "there is no such thing as a bolt on". I think that I can extrapolate that in the case of a conversion to EFI, there is no such thing as a plug in? There is always going to be a bit of finagling involved.
I once saw eight oxygen sensors installed in the primary header tubes and the complete flexibility just complicated tuning the engine and the effort didn't help.
Ironically my older son sees me as the "carburetor guy" and criticizes them as barbaric. He reburns cpu's for production high performance Fords.