Spark advance was originally controlled by a basic computer and manifold pressure sensor (MAP) I expect manifold vacuum will be variable on woodgas so replaced the distributor with an earlier one that has centrifugal advance and a transistor ignition module, it's the finned box on the spring tower.
I added the simple LPG mixture controller pictured along with an exhaust oxygen sensor, and ran the 5 volt feed wire from the removed MAP sensor to the forward throttle position sensor (TPS)
The front and rear gas locks and the LPG computer are wired to the ignition circuit, via a safety relay, and are now always on while the engine is running
The yellow inline lockoff will allow a small amount of LPG to the intake for hybrid running, and should regain the power loss expected with woodgas.
It picks up gas after the LPG mixture controller and is switched on/off by the rear throttle position sensor (the rear TPS has a 12V reference voltage)
The blue vapour lock at left switches LPG to the mixer ring on/off, and is switched together with the converters' forced idle solenoid
Air leakage past the two large throttles gave a high idle speed, throttle stops are backed right off and idle air bypass passages have now been blocked
The glass vacuum bottle in the rear corner lifts water from the trap at the bottom of the firewall.
The inline lockoff on the firewall above it switches manifold vacuum on/off and gives a controlled bleed of woodgas for idling.
This lockoff and the rear TPS are switched together