After 45 years on bikes, I am afraid the odour of my piss is like gasoline.
The size and the type of a turbo for a certain type of a bike is not easy to estimate, but there are some common facts that may help, I think. If specs, dimensions, and other facts are available, then the estimation should be not so hard. When dealing with the turbos of cars, those facts may not be easily found. Nevertheless, some information is available allways:
Water- or oilcooling. This is vety simple. If your bike is watercooled, both will fit, if it is aircooled, be sure that the turbo does not need water circulation.
Dimensions and ports. There is a huge variation. Also the weight is important when you are hanging the blower somewhere infront of cylinders or under the saddle, your ass is also in the dangerous area! The plumbing is easier if the ports and pipes are originally showing in suitable directions.
Then the difficult aspect: Capacity of the turbo. When fuel is burned, it produces certain amount of gases. In my case, GSX400 consumes about 4 l/100 km and I was looking for a car with around the same consumption, what was not so easy when speaking about turbo-charged automobiles. Also the primary goal, increased power, counts. My goal is around 50-60 hp which should be achieved easily with a small charger designed for a car. No matter of the number of the cylinders, if it is two or more. This has been proven scientificly.
All above is still just theory. The thing that I am worried with the GSX400 is, if it will take the boost without breaking apart. I consider, I learnt my lessons years ago after several craters and holes in the pistons lf my bikes, but i am not sure yet.
My mother tongue is not English and all the stupidities are results of that fact. Readers have all of the responsibility by themselves ;-)