I had a Westfield with GM's ASTRA GSi 2.0 16v twin cam engine in it , That should have run with a computer for the engine mapping , ECU , start , and linked to the speedo etc etc . No more auto choke .
The builder , removed all that , put on an ignition advancer and that was it .
Started all the time and ran well , although a little rich. maybe the weber 45 had something to do with that .
But otherwise , why not , there will be a simple solution to that soon , maybe a plug in circuit board to talk to engines that all the sensors are alright despite not being there .
Gearboxes ?? No idea , but the Westy had an XR4x4 gearbox , RS2000 brakes and rear axle , so , maybe possible.