I built a diff a few years back and did like above, got an extra bearing and ground it out a few thousandths so it slid on and off easily. Don't want to grind away too much though. I cringed at taking a grinder to a brand new $30 Timken bearing but it worked great.
There are actually 'checking' bearings available now for this exact purpose. Check Randy's, MW, Ratech, DTS etc. Not sure who sells them. I got my extra at a transmission supply house before they were available.