Bingo.
The advantage is that D-Series engines cost less to start out with and parts are generally less expensive. But I seriously doubt that dude wants 400whp anyway.
To the point. Put a $1500 homemade turbo kit on a Z6 and you can have more than B18C5 power for significantly less money. Hell, you can get K20 power for that price. If a B-Series is what you want go for it, but don't just jump on the bandwagon because you don't know what D-Series engines are capable of.