The lower has no issues with the added power besides the prop shafts...it will shear the factory roll pins in seconds... all my prop shafts are pinned with hardened drill rod for this very reason...down fall with that is they will toss the drill rod occasionally on the 30vg....
as far as your stainless plate,,,just be sure its not thicker than the stock arm by much or it will mess with your trim adjustability... my ss plate i get is .052" thick...right in the ball park of the factory arms.... i take a factory arm,,,flatten it,,and tranfer that onto the ss...drilling it can be tough,,it kills the tiny bits perdy quick..... easiest way ive found to cut them out is a cutoff wheel in a dremel tool,,after they are cut... i use a small belt sander with 120 grit paper to clean them up and make them the same overall size...quite simple,,just tough material to work with....