There all a bit direct for HK-47. He would be very subtle with Palpatine, something like changing the oxygen levels in the Death Star etc. (I know he'd survive but something along these lines).
This post does derive from Escape wrongly thinking that me and Fishy though HK would defeat Sidious in a straight fight. That thread referred that Revan would have to assasinate Sidious and other Imperial dignitaries, "assasinate" not kill.