When I went to solid lifters I also swithed to the factory adjustable rocker mounts. Made for super easy setup on the lash. As far as the flywheel, def go with an aluminum adjustable timing for better throttle response & you can advance timing for better powerband, hp & tq.
Far better results decking block than milling head, some pistons sit .060 below top of deck, tisk tisk kohler power gods.