OP, you sound a good bit like me. I was very close to 60kg at racing weight running before my injury a two years ago. 20' best is 320W, so if I got back to that I'd be near 5.5 w/kg for 20'. Should climb well on that...if I get back there. Currently around 68kg.
Dunno quite what qualifies someone as a climber though, but my plan is pretty much to just start racing to gain experience and actually see what I perform well at in races; while still keeping a focus on Sunshine, Guanella, Evans, and especially Pikes Peak.
I'll probably be racing you this season if you're a 5 and coming out to any of those.