http://www.customclassictrucks.com/techarticles/0405cct_vortec_cylinder_heads_small_block_chevy/index.html This will answer all your questions. Yes it can be done. There's a bit more to it than just torquing on a new set of heads, but if you can replace heads, you can more than handle the rest of it. Should flow much better than the stock TBI heads. Vortec heads flow far better!
245 hp.
285.
i belive its 160 or 180 if its a vortec
255 HP from the factory.
295 without modifications PER GM Website!
Chevy never made a 327 vortec. the last time they produced a 327 was in 1969, while the first vortec was made in the early 1990s.
250-290 hp
I own a 93 Chevy Silverado K1500 4x4 with V8 350 TBI 5.7L. so unless Chevy has changed their blocks, i would suggest that naturally your block is a SB 350. However, since your question was about horsepower, not which block you have, I will tell you the horsepower. The 1998 Vortec 5.7 liter makes 255 horsepower.
in 95 they went to the vortec engine but a 94 (like mine) had 200hp and 300 ft/lbs torque from the factory
Probably about 240 or close. Move to a 96 and it's a lot more. The Vortec started in 96 with the 350 (5.7) and 454 (7.4). I understand the Vortec 5.7 had a little more power than the non-Vortec 7.4, and the Vortec 5.7 has 250 horsepower.
There are 4 different Vortec engines for that year. Stock horsepower at the crank are: The 4.3L (262ci) Vortec V6 has 190hp The 5.0L (305ci) Vortec V8 has 230hp The 5.7L (350ci) Vortec V8 has 255hp The 7.4L (454ci) Vortec V8 has 290hp
175 hp 205 ft lbs of torque