Ignoring budget completely, there are only a few ways to get 300whp out of the L36. Turbos have the most power potential, SCing it is pretty close as well, and then there'* the all out N/A performance part engine. The fastest N/A GP was around 330whp last I heard, that'* with a lot of top parts.

Nitrous is a viable option as well, although to get 300 hp you may only be able to spray a few times before the motor gives out.

Who is this? Last I heard it was 250whp.

The highest L36 dyno is 270whp but thats in a f-body configuration. (abbot racing)
FWD it'* 250 whp. (zzp)
With a g you may be able to get to or a little over 200 whp.
If you don't want to mess with your transmission and you're happy with only being able to eventually make 230ish whp, then get the zzp gt1 cam. That isn't going to leave much money for bolt ons but you can always do those later. A pcm matched for the cam should go in at the same time though.
On a wbody it dynoed 199 whp with a 3" DP, cutout, pcm, stage 1 tb, and intake.
If your not mechanically inclined enough to install the cam then higher ratio rockers are the way to go. ZZP'* ER ratio are the best ratio. Add an intake, high flow cat, pems, a HV3, and some sort of tune, money permitting.

Maybe I'm misunderstanding something, but isnt the L36 listed at 205HP, or is wheel horse power different from regular HP?

Yes, the L36 is 205 Crank HP not wheel horse power. Quite a bit is lost beween the crank and wheels

Exactly.

If you assume a 15-20% powerloss through the drivetrain, your car is putting down about 165-175hp at the wheels.

Anything is possible. About 5 years ago I threw about 15 grand and hundreds of hours at a 3100 V6 race car and put over 300 HP to the wheels. It all depends on how much money you want to spend. You've got to ask yourself if all that money is worth it, or would you rather buy a faster car? Or would you rather save the money and keep your Bonneville (and no Bonneville is a slouch) the way it is?