Regards your Valiants & LPG don't worry about power loss I recently converted my Magna (Not an inline) & experience no power
loss. Modern LPG is a big improvement on old systems.
Also old tractors often ran on LPG the manufacturers upped the compression ratio to minimise power loss, something you will probably do to your Val any way.
If you go to the Ginger factory in Buderim you will see a Chrysler flat head race car.
