Torn between 360/408 and 440

It all comes down to what is it you really want? Do you want to say you have a 440 Dart, then put in the 440. If it is strictly a target power you are after, a 408 will likely get you want you are after in a more compact package. You already know what you have to change to convert to BB.

I believe dollar for dollar, you will get more output out of the 440.