Is your block a roller cam block, or a flat tappet block? Just making sure your Vortec heads are on an older flat tappet block, or that you're not running a flat tappet cam with roller lifters.
204/214 is relatively tame, but those heads are nice flowing factory heads. I'd put the power in the 285-295 range. FWIW, stock LT1's ran similar lift with less exhaust duration and made 275-300 (F and Y car), but on roller cams.
If you want a good street motor, I wouldn't go much over the low 220's duration. As noted before, watch your valve lift with Vortec heads. You can go larger on lift if you put LS beehive springs with the right retainers and locks. It's a $150 mod that will get you up to 0.525-0.550" lift safely.