All sorts of shocks have been used on those frames (258, 058, 7007, 9007) by owners on here and mtbr. Rockshox (monarch xx, rt3), fox (dps etc). The frame has a pretty middle of the road leverage ratio, the 165x38 shock with 100mm travel being a very common combination by many manufacturers over the years. So, a shock with medium damping should work. Given the frame has a high pivot (so reduces Bob), you might get away with light damping, unless you are a heavyweight. I run a manitou MacLeod on my 058, and it works great.
If you get the frame, make sure you get the right size shock hardware. The top shock mount appears to measure up around 21.85, but will fit 22.2 with some very minor force to get it in there. Through various threads (on here and on mtbr) it looks like a pattern has formed - those who made the mistake to get 21.85mm hardware for the top shock mount have ended up with some play in the suspension. This includes me. After nearly a year of ownership, it is still minor, but I have ordered some 22.2 hardware to finally fix it (hopefully).