Mechanical tach drive

Ok so Im working on the engine rebuild and have the tach drive all in pieces .
I have new oil seals for the distributor and tach drive pinion .
The pinion gear seal looks just like a regular oil seal .
when you look at the parts breakdown it shows a retainer ring and a seal . #s 122/123
The seal I have is the same O/D as the retainer ring . The only way to get the existing retainer ring out is to collapse it in on its self and destroy it .
So my question is ....Is the new modern style seal in place of the old retainer ring and rubber seal .
Or do I leave the old rubber seal in and add the new style seal on top of it ?

Anybody ??

Here's a better view:
https://lbcdigital.com/bmc_publications/akd1151/

Ideas besides leaving it as-is:
--maybe you could tap a sharp awl between the base of the ring and the seal rim - to get enough space to insert a small screwdriver and gradually pry the ring out
--remove the bush to the bench. Pull the drive pinion and make a shouldered shaft similar to that of the drive pinion, but longer - use it to push out the seal and retaining ring.
--maybe you can use the pinion itself to push the seal and ring out.