1970 Chevelle questions

[442w30]

Please tell me if this timeline is correct:

- At the start of the 1970 model year, the SS 396 was available as an L34 and L78, plus L89 heads.
- Soon, the SS 454 package with LS5 was introduced.
- Then, perhaps in November 1969, the LS6 was added to the SS 454 package, replacing both the L78 and L89.

So, what I'm curious about, was the LS5 available concurrently with the L78/89 before the LS6 was introduced, as above? Or was the SS 454 package a complete replacement for the L78/89?

Thanks!