The Flux mount really won't work with the FLM. It actually hangs out past the TVP on a special lower motor plate. You don't really need it though. The stock FLM mount works great. The single speed tranny will bolt right into FLM's chassis, as will the new bulkheads.
The more I drive this truck, the more it reinforces my belief that a lower weight is the way to go for performance. Start ditching all the aluminum and stick with plastic whenever possible. Alloy looks good, but in the end it hurts performance and leads to other parts breaking. Except for Integy parts, they give you the flexibility of plastic with the looks of alloy. At least for the first crash.