Ask ken about squish, billet thrust washers and ear reinforcement if he says its not necessary turn around and go home with your motor and find someone who knows more about the zilla's
Warmeck, these guys are just looking out for your well being. That is a very nice quad for $400. In the end, it's your time, your $$ and your engine to do as you see fit. Just make sure your builder fixes the known problem areas.