depends on where the vin is, but its not a special or complex security stamp, its just an embedded number, look at it this way some accident cars are usually rebuilt / refurbished, actually some of the imports are refurbished cars thus in some instances a 8 year old car with very low ‘genuine’ mileage, once refurbished they reset the odometer. I think if someone is willing to break the law and smuggle in a car from ug, I think the vin would be the least of their worries.
Still in this particular case it would be cheaper and less cumbersome (especially legally) just to import the parts, or buy the car and have it dismantled in japan and have the parts sent.
As long as chassis is the same, yote yawezekana - legally. You could even have the donor car cut and import as nose-cut, rear cut etc. No need for Uganda magendo gymnastics.
What I know is that you will regret. These things are not easy as you think. If you are not an insider in the business, chances that you will get stopped at gunpoint are very high.