It can be an expensive proposition by the time you replace the drive shaft ,shift shaft and water tube on the engine. If it is an older engine it may not be worth it unless you can find some used parts. Often on older models by the time you add parts and labor you will exceed the value of the engine. You may want to give us the complete model number so we can steer you in the right direction. Its possible, maybe we have some used parts from another conversion .
Like stated above we need the model number. You can cut the water tube rather then replacing it. I have a phone number to a guy that can cut and machine a new spline into your driveshaft to save you from buying another shaft. All you really need to buy is a shift rod.