Either main size will work well with a 4.25" Stroke. Personally I'd rather have the strength in the caps and main webs and use the smaller but still graciously adequate 400 main journals...but opinions vary.

With a 2.200" rod journal and a .990 pin (not to mention the minor reduction of the counterweight diameter itself to clear the webs) you're reducing a lot of crank mass compared to the heavy (and less precisely balanced) OEM set-up.