The 128 rule is for finding the ideal LCA, not LSA.
I'd agree that in this case, with the OP's goals and engine combo, the narrower LSA is more ideal. A wider LSA has it's place, but would depend on the combo and the goal.
I've seen some of David vizard's videos and have a book he wrote, he talks LCA alot not LSA and have read in the forums that a LCA and LSA are the same.