> About how much horsepower can I put to the
> stock tranny in a '79 ZX?
I assume you are referring to the original 5-spd and that it hasn't been rebuilt? The stock manual transmissions in new condition can handle in the 300 HP range. Due to the specific gear configurations the 4-spd's are actually more durable than the 5-spd's. The abiliites of your trnasmission will be entirely dependent on condition and how you drive it.
Hanve fun - but not more than you baby can handle!!!