IMHO -I would get someone else to take a second look before I decide to do an engine swap. It's probably something right in your face that you're overlooking...
'11 328i (sold)
'07 Audi A8
'03 745Li (sold)
'03 Acura TL-S (sold)
'15 Toyota Sienna Limited Premium w/Dynamic Cruise
'15 Infiniti Q50 Premium w/NAV & 19'' Wheels