When I was about 8 or 9 we used to have a 2door rangi, the engine was abit sad so oneday Dad decided to change it. He aquired an injection engin out of a car which was soon in the rangi, the only problem was that for some resson the bonet whould sit on the plenum chamber when you closed it.
So, after lots of swaring ( bad for an 8 year old to hear ) the injection was removed and the carbs off the old engine were fitted and later a modified manifold and a twin choke webber.
The thing would go and sound like nothing on this planet ( 8 year old remember ) but would only ever do 7MPG. Stick with the injection.