I'm Redoing my 03 400 ex, and Im looking at picking up an 07 bottom end with reverse. My question is does my 03 head compatible to fit on the 07 bottom end? Also are there any other suggestions for doing this swap.

Thank you

 

It doesn't look like anyone here has tried it, so my advice is check the on line parts books for the two model years, and see if the parts you want to swap from the earlier engine have the same part numbers as the late engine. If they don't they may not fit, but if they do, you know they will swap.