I am going to play Devil'* Advocate...
I'd put my money on the Grand Am GT.
If your Bonneville is stock, which you say it is, and the Grand Am GT is stock, which you believe it is, you will lose.
My mom has a White 97 Bonneville SSE and it couldn't keep up with my Grand Am GT back when it was stock.
However, after having said that, even after the removal of my intake resonator, new plugs, and running drag pressure in my tires, the Grand Am GT still can't catch my Galaxy Silver 2000 SSEi. It would need NOS or a supercharger to stand a chance.
If you don't believe me, check the 0-60 numbers. Naturally aspirated Bonnevilles running 3800'* with 205 hp and 230 lb-ft run 0-60 in roughly 8.2 seconds. For comparison, I have never read an article that put the Grand Am GT running a 3400 with 175 hp and 205 lb-ft over 8 seconds for the 0-60 mph run. Want proof? Check Edmunds.com or other auto comparison sites.
That'* my two cents.