Actually, I think I know the answer, maybe there's a more definitive one.
What residential avenue was primarily replaced for the 405 ROW through the valley ? Primarily, I mean more sq. footage of this particular avenue name was dug up more than any others.
My refs were a 1957 Thomas Bros. map book, $2.00.http://www.flickr.com/photos/hgrpix/8270969780/in/photostream (http://www.flickr.com/photos/hgrpix/8270969780/in/photostream)
and current Google Earth.
I have waaaay too much time on my hands since I've retired, but it was fun.
There is a cool old maps of I-405 in back in 1962 some were complete, proposed, and under construction. You are welcome to view any kind of maps in other area!
https://www.aaroads.com/forum/index.php?topic=4456.msg98749#msg98749 (https://www.aaroads.com/forum/index.php?topic=4456.msg98749#msg98749)
Enjoy!
I know the north end of Sepulveda was replaced by the 405. Originally, it continued past Rinaldi to connect to what is today just a short stub around Roxford Street that also carries the Sepulveda name.