Recommendation for head bearings?

[shrekster]

I'd go with tapered roller bearings every time, pack them well with grease and you'll probably never need touch them again. There is a supplier listed somewhere on this site, i've used them before and their service is first class. They also know exactly what bearings you will need and won't supply cheap cr*p.
The standard ball bearings need carefull torquing up to get the adjustment right whereas roller bearing are far easier as they can stand a fair bit of preload and still work ok.

Jim.