Asking a quesion like that in this forum and you can expect answers like stryder's.
Forget the 351W. The 400 can be made to run well, but is limited in the performance parts dept. For simplicity's sake, stay with the 390, although I'd verify that it is truely a 390, could be a 360. The fact that it is 4wd means that it is most likely a 390 though. Rusty's comments about a 390 are pretty much right on.
However, I know you said less than 400 cu inch, but if you have the $$ and time, your other good option would be a 460.