Hi just want to add some practical advice on this subject of drum bearing swap, don't think about old drums, not worth the trouble just get new ones originals must be scrap by now!
done my rear drums (new) did consider going to a garage to press the inner bearing collars, but I read more on the subject and did it my self with no special tools, this is how I did it: 1) get a small retractable long hobby knife and de-burr the first edge/lip the collar sits in to help the initial fit. 2) place the 1st new drum studs down and heat the neck where bearings sit with a cheap blow torch in a safe place outside on concrete or the like, any oil will soon burn off, slowly turn it around with suitable glove on one hand, torch in other till it is very warm only. 3) take your collar thick lip of taper first, (grease outer diameter first) and drop it ready to be worked on in place. Having an old inner race spare I then dropped that where the new one will go later, got a large socket about 44mm OD /34 ID on that (see what large sockets you have to fit) and lined everything up to start and tap the lot with a large hammer (lump hammer best). Gentle to start with till it goes in the right bore just a bit still square to the that bore. 4) Not forgetting the drum is still pretty hot still, but more lubrication is needed to cut down on the bashing and causing damage. As the parts are now there is a lip to spay some WD40 in (as long as it is not too hot) And start to hammer moving the old race and drum around keeping ALL square still and you should be getting close to your shoulder lip/stop that the collar is to sit against now, keep checking and stop hammering when there is no gap on the shoulder. 5) Flip Drum over and without needing to re-heat do the same exactly to the deeper bore which I found easier, thought it would be harder, but de-burring and lubrication help allot. BTW I did not freeze the collars as they are so small it would not have made much difference anyway. I checked the surfaces for damage and could find none so ready with ALL braking parts in place to fit drums to hub shafts now with grease/seal inner most/ABS ring/ taper races, more grease/ new large lock nut/cap All fitted as manuals specify. Both sides must be done at same time of course. I expect this to be job done but will report back if anything does crop up with this drum job in the future? BTW I needed new drums due to wear, a lip showing on brake surface making brake adjustment very limited even with new adjusters/shoes and cables. taking the lip off will just help fitment on a out of spec drum. Hope this helps someone with their rear brakes.