The problem with your logic is, he already has 2.02's in the X head and doesn't have to spend a dime to upgrade the other heads which are inferior at present. Not all heads port out the same. While the early castings can be ported well, I have not seen them go as well as the XJOU.... heads. I know that doesn't mean someone can do that work......
The 2.02 can indeed make 20+ HP over a 1.88. No question. Seen more power differences between the two. HOWEVER! It is also the combo tested that shows a big or small one. Even mild builds have a good spread.
At this point, I can't see selling the X head to roll the sale cash into a smog head that starts with getting rid of 1.88 in favor of a 2.02. IMO, that is just insanity.