There has been lots of discussion on the VansAirforce RV-12 forum about the John Deere Rectifier/Regulator. A search came up with THESE
The R and B terminals are connected together inside of the Ducati case. Therefore, splice the aircraft R and B wires together and connect them to the John Deere B+ terminal. All of your assumptions about wire connections are correct.
The Ducati regulator.
The John Deere "Ignition Switch" terminal must be connected to a switch and NOT directly to the main power bus or to the battery contactor or to the B+ terminal. If not switched, the pilot will not be able to shut off the alternator in the event of smoke in the cockpit, even if the aircraft battery is disconnected.
Individual spade connectors are a good idea because the connections can be tested individually for tightness. If the connections are not tight, they will get hot and cause damage.