Ok, your sig says it's a 96.

The stock vortec heads are only good for .470" to .475" lift unless you have machine work or after markert / GMPP aluminum heads.
If you try to use more lift than that you will pinch the oil seals and break the stock springs.
I went with a comp cam (I'll get you the numbers when I get out in the garage).
If you add 1.6 roller rockers like I did, the lift will be too much and you'll pinch and break like I did. This is why I'm installing the LS1 LOL!
The vortec motor will idle rough if you go over .214" on the duration so you would have to install a stall converter and some custom programming beyond a Hypertech or compatible programmer. If you look at the combo in my sig, I was putting out somewhere around 340 to 350 HP without the Nitrous.