94 v6 to v8

I got a 94 3.4 V6 firebird earlier this year for $1000. But im not satisfied with it i Like most people want more horse (it only comes with 160 stock) i thought about doing some mods on it but i dont think the overall horse is going to be enough to saturate my thirst. So im thinking about switching engines to a 8. Now heres a few questions How much more horse does a 8 have and am i going to have to modify the engine compartment alot to make a 8 fit? I can get a good deal somewhere down here for a V8 and a tranny to go with it im sure so i just want a few knowledge before i go through with this