I'm in Oklahoma! LoL. When I was living in San Diego I had IMM in Indio, CA (2.5 hrs) do a 510hp 416. That was before I met Mitch Cogswell. Chula Vista was only 40 minutes from me.
If you can't find a machinist or builder that is a Mopar guy in the LA area you could also check with Motech in Murrieta and see who they use(Inland Empire Area). Someone was in Ontario as well but can't remember. Try to find Bob Mazollini's people in Riverside.