I had some time this Morning and took another look through the files and found this memo. While dated for mid '69 it does provide insight into engine carryover to '70.
The complicating issue with the memo and our topic is the Continuation of the '69 body well into '70 with Chevy calling it a '70 and then followed later by the "real" Chevrolet rollout of the new '70 Camaro in February.
Notabily both Colvin and Hooper agree on M-40 as an option on L-78 as follows:
Hooper in his book "The Illustrated Camaro Recogintion Guide 1970-1973" first on page 63 listing "CJL"- and later on page 129 - "Manual or automatic Transmission was available in any SS Camaro".
Also Colvin in his book "1970-75 Chevrolet by the numbers" (on page 58) actually lists two seperate three letter codes for L-78 Camaro and TH in 1970. CJL and CTY. Colvin however does not discuss the carryover engine issue which could mean that when the CJL carryover engines were all used then CTY could have been the later (post) February '70 Camaro L-78/M-40 engine.
Time will tell
Phil