Shay, that's the 64 K question for Verner S-3 installs. Les Homan is probably the top guy on terms of hands -on experience in experimenting with engine mount design. Frank Johnson (Performance Propellers) and another guy in Texas are doing work in this area. The Texas LE birds have their engine mount pickups right at the four longerons on the firewall.
I don't know about the California guys, except to say that some 20 S-3 engines have been sent there so alot of people are going to have to focus on this.
I don't know of any completed mounts. Liability concerns affect the availability of plansets.
Again , Les Homan's videos are an excellent way to keep track of the ( Californians) engine mount developments.
Cheers,
Nical