Anyone happen to know how much HP we can throw at her w/o worrying about drivetrain problems?

all the power you want, just dont put it with sticky tires and you'll be fine. Throw on some slicks or something and THEN you will break stuff. Usually the driveshaft will be the first to go, but the rear end might be also, Im unsure as there arn't many people running slicks/pushing the limits of the stock parts.

Hmmm...what about drag radials?

Don't worry about it until you get below a 1.70 60-foot at the track. The stock parts are fine until that point, then stuff will start to break. Wheelhop will also be more harmful than a dead hook.