ya i would try it on a spad before anything else thats nitro powered. if you have electronic equipment maybe a cheap plane (gws slowstick) that can easily be repaired and is much lighter so will need a much smaller chute for testing.
also remember that your airplane is still getting lift from its wings while falling, if you put to big of a chute it will never come down
i would, just incase something bad happened (i/e chute gets caught on tail), have a parachute release system to deattach the parachute.
good luck,

btw the electrics would be ideal because if the chute idea were to fail you could drop it and restart the motor.