Went to tapered rollers on a Honda CB750K8. Waste of money. Clean, grease, adjust properly your stock set-up and you'll be good to go, unless, maybe, you're going racing. I've refurbished a dozen stock set-ups of all the Japanese manufacturers and they've all worked perfectly, if you take the time to set them properly afterwards.
http://www.xs400.com/forum/showthread.php?t=6730&highlight=steering
Ride the *&^%$ out of it? On a 400cc econobike? Oh please. Keep yer money in yer pocket, and stay stock. Once you have a properly sorted stock system, then, IF you STILL feel a need for an upgrade then go for it. An upgrade to cover up a poorly setup stock system seems like a band-aid at best.
*off soapbox*
Kirk