It can handle a lot, but the issue is the fuel system is limited to producing the any high HP and torque. What are you trying to do with your 96 vortec???? The 96 and 97 was an odd ball year for PCM tuning and the 95 was even worst.
Good luck, but it can be done. I have a 96 with just under 225HP at the wheels with the PCM Dyno Tuned with intake and exhaust upgraded.