Nice work...were the old bearings bad? Or, did you just want to replace them? DSS has a rear wheel bearing retainer tool,not cheap though. I bought one several years ago but had to return it, the manufacturer was off a bit and it didn't quite fit the old or aftermarket retainer. They sourced a new old stock retainer suspecting the retainer. I had told them it was an issue for both, but they had to verify for themselves. They worked with the tool supplier to get it corrected. At the time NOS retainers for the 550 and 500 were hard to come by... They pulled the tool from their catalog until it was reworked to fit properly.
I was able to get it to engage 3 of the four holes, enough to work on the hub.
At the time the tool was around $60 if I remember correctly.