There have been several lanky fighters with top punching power (Foster, Hearns, Arguello, Spinks etc), but lanky fighters that are physically strong? Morales is the one I can come to think of straight off that fits the description. More picks?
Thought of him, but couldn't really decide whether he was lanky or not. Felt he was a bit more filled out than the ones I mentioned, but I see your point.
This is a matter of definition of course, but guys like Monzon and Froch are sinewy but not lanky in my view.
Alexis Arguello. Great inside fighter despite looking the opposite. Mancini was bull strong but Alexis was not out-muscled and bulldozed him at the end.