TBH, if you are using it for cross, stick with the chainset you have and get some bigger rings, but go to a double. Most CX racers are using something about the 42 size as a single ring or a mid30s/mid40s doubles. (something like 36/44 is not unheard of)
If you go to a road chainset (octalink, isis or square taper), even with the proper bottom bracket shell (73mm) you may have issues with the inner of a road double (or the middle and inner of a road triple) catching on the chainstays. Most MTB rear ends are designed around significantly smaller ring sizes. So you'll have to go to an axle which is far too long to hit any sort of a decent chainline.
And road triples, not really suitable for CX, the big ring is too big, and the small ring is too small......... unless you are Sven Nys, then you can ride whatever you like.