Here is the thing. Fashanu is a more finished product to Chop, so when/If they went against each other, if Fashanu won against Chop, that could quickly change when Chop is able to fix his wraknesss.
Now If Chop looked better, well let's just day we got a very good player. Either way, there is no way of know if one, both, or neither can succeed in the NFL until we actually see them.
One story I heard, Michigan (This past season's National Chmps), had to change their offense to run way more, because when they played Penn State, Chop was becoming a huge issue vs the pass.