400 or 440 Stroker

I currently have a stroked 400 in my dart, and I am wanting to start slowly getting together parts for a more radical build, maybe up around the 750 HP range, I am wondering, what is the better foundation for a new build. Should I do another 400, or should I "upgrade" to a 440? I'm not in a hurry because my current 499 is running just fine, but I'm going to slowly get the parts together, and I wanted opinions on what the best of the two options is.