Love these cars as well. the "Super" class needs to make a comeback imo. Super Nitro Rallys are great, and there are still a boatload of parts out there since they share much of the same parts with the MT2. Don't really have much issue finding parts for mine, though the plastic suspension arms are getting a bit rare. (aluminum ones are still floating around though)
If looking new, the WR8 is dimentionally identical to the old Super Nitro/SNR. It is a 300mm WB as well, so it fits the Toyota body.
The only issue you might have is the front shock tower on the WR8 looks to be a bit tall, and the nose on that Toyota body looks to be low. Don't have one to compare to my supers, but only thing I can think of that might give you grief.