Well I guess that's why those seals have such a bad reputation - if so it is a bit unfair there aren't many vehicles that have easy access to a rear crankshaft seal with the engine fitted in-situ...
...Oh I forgot to say that start ring job: Well done! My series 2a flywheels were really not going to give that bad boy up. I drilled and drilled and smacked the heck out of the ring at several places (thinking the book must be right) but got nowhere. The starter rings fitted to my flywheels seemed to be way too malleable to snap like yours did. I ended up sourcing a complete new old stock flywheel with the ring fitted.