Get some JB Weld in there while you're at it, won't you? NO!

You need a good ball or needle grease. Most kinds of wheel bearing grease work fine since we don't get the heat associated with wheel bearings, but you need to make damned sure the grease gets INTO the bearing assembly, not just lying around on the outside. Put some grease on your thumb and slide the thumb across the bearing edge, forcing the grease into the bearing and out the other side. Repeat until you've gone all the way around. Do not grease from both sides as that will only give you an air bubble in the middle.

Oh, and remember to put the races back in the right way around. They're tapered to allow for adjustment - when you tighten the nut, you effectively force the bearings 'uphill' the taper, making them tighter. Tighten it so the steering head swings freely (no snags or hesitations anywhere, check the cables and take it for a spin - you should not feel or hear a 'clicking' sound from the head when braking hard. If you do, you need to tighten it just a wee bit more.