I had some very bad luck with the 904's anything that could break did break. the 727 held up and never puked on me. Just me rabbling on, take it with a grain of salt....
Well I guess it depends on the use. This car will be 90% a Street Car and 10% for the track. It will NEVER hook on the street so the chances of it living with a 904 are very good. When you start hooking a car you WILL break everything that is weak that is for sure.
One thing to remember, a Turbo cars power will come on Linear. In other words it wont have drive train SHOCK that a BIG NA Engine would have. So the Initial SHOCK will almost be non existant, I guess that would be called Lag. A NA NOS Engine with a Transbrake would be a whole different story.
DODGESTRIKE Did you asked more about using the 904 on your application or is the 727 a must ?