From 1995 and to present, how much HP could the manual transmissions in the Z24 hold? I am buying a 1997 Z24, 5spd and I was curious of a HP number? Anyone know?

It's rated at a max input tq of 225 ft/lbs. If it's taken care of well, you can probably get more out of it.

Is that so much the stock clutch or components inside of the transmission? If components, are other Isuzu parts better to swap out, and if so which ones?

Since it's a manual, there are no clutch components inside the transmission. The gears are constantly meshed.

The clutch (on the flywheel), I think will fail before 225 ft/lbs. So you're going to need to upgrade to a Stage II or something. Normally the first thing to go will be the spider gears inside the diff. It's cheap, it's weak. But that's because GM went and made stuff cheaper. So using the Isuzu parts would be an upgrade. You can use stuff from an Isuzu Stylus, or Geo Storm. And one other car that I cant remember. I think even the diff. in the 93 2.2L Cavaliers is stronger than the 3rd gen cars.