So, a two speed isn't an option. When I looked at the gearing charts for the two speed I realized that second gear is always 1:1, so that doesn't really work with any realistic rear-end ratio I would run.
I'm actually looking now at a G-Force GSR transmission. It's configured similarly to the Jerico, but the G-Force has internal shift rods which allow the shifter to be centered in the tunnel. The side shifter and external shift rods on the Jerico look like they're going to cause problems in the RX-8 tunnel.