There's not really an answer to that question since there was never an official David 4 released. So none of the morphs would be able to be used as a base. You would need to make content for the M4 base and then add whatever morphs you need to simulate a David-like character build. You could probably get pretty close with the M4 morphs++ package, the same way you can get close to a Freak shape. 

There may be a way to transfer the David 3 or David 5 shape to the M4 shape via DS and probably the help of zbrush or mudbox (I don't think blender has the ability to project shapes onto a mesh but I don't know. I know it can be done in zbrush). But if you were to go to all that trouble, might as well just use the real David 3 or David 5. 

 

~Shane