Why are you so set against the NK? I had a 353 that rocked with it.
Hopefully you don't have a narrow kerf bar and chain on that saw - if so, change to regular .325, and use LPX chain (BPX or RM if you want semi-chisel).
Try a .325x8 rim instead of jumping to 3/8", .325 is nicer to use on the smaller saws. The "gearing" will be slightly larger with .325x8 than with 3/8"x7.