I'd still just grab a Cain 2-bbl or Ultraflow 2-bbl intake, and shove a CA 300 on it The best distance is the shortest one, and both have good runner volumes, and not have to worry about any more tha about 1.2 liters of gas going boom if you had the advance up to far.
If an ex EFI unit its used, I'd say the 12 years old EF/EL/AU/BA/BF unit mated to the XE flange or rail.
Look as Dynoed 250's blue Cortina. His adapted unit uses the XE rail tig'd up to the EB Multi one piece plenumb. Do that with the XE rail and the upper and lower EF plenumb. Eliminate the dual resonance flap, keep it closed.
The later EF to BF manifold is only about 3.5 litres by the long path, and less than 2 by the short, so it should be okay to stop lean backfires on propane. Be great if you could stop the back flow of unburnt gas entirely using the dual path flap as a six port throttle blade. You could advance the heck out of it with good part throttle economy, and no lean backfires on over-run, the bane of all charged intake propane systems. Oh well, we can but dream!
You know, I still cant believe that its 10 years since the Bioquip/Parnell injected EFI propane system was shown to the SAE in an EF Falcon, but were still trying to find ways to stop fires in the plenumb, before we even make it push pistons down. Maybee addo is right, just use the old oribble Vaccum Governer like the Inter LPG truck had, or worse, the VC Commodore 4's five second delay when you lifted off the gas!.
Hey, I know. Just use the IAC steeper motor on overrun, and wind the ignition back 10 degrees. Then you could run 40 to 45 degrees total lead, and then drop it back to 30 or 35 when downshifting.
