i say if u have the money and the means to build the b-series engine. go with that . you will get plenty of power out of a turboed d but im not to sure on the reliability of the engine at that point. im sure u can build a reliable bosted-d but to run the same numbers as a boosted-b the reliability might be lower.... now this is all my own understandings so im sure others will chime in and corret me if im wrong...