id take out the cabnits and build a hood in there place and just use ducting to duct it to your fan...i think its ur best bet... i dont think u need a strionger fan.. a 1350 cfm is what i think u said u had.. that should be good enough to clear out that space.. make a hood and duct the rest and ull be fine...make sure you use 16" ducting other wise ull loose CFM