As you may be aware, the 66 Shelby GT-350 street version came with 306 H.P. The engine was a 289. It was not stroked, nor did it have major head work. It started as a 289 Hi-Po motor and was enhanced from there using a cam, carb and tri-y headers.
I realize that we measure horsepower differently these days, but nevertheless, I think you get the idea. A 302 is not a major departure from a 289. In addition to the items stated, compression ratio will be a factor. The Shelby 289 had a 10.5-to-1 ratio I believe; maybe 9.5-to-1. You can check it out.
In this day and age, assuming a healthy bottom end, a good set of breathable heads, correct carburation, a cam on the plus (+) side of "mild", a good set of headers and dual point or electronic igntion, combined with the correct compression ratio should get you there. It's almost ALL bolt-on.
In 1967, I was an original owner of a new 1966 GT350. I paid $4695. It was totaled in an accident in 1971. I still have the steering wheel.
Current project is a 1966 Fastback 289 that I have owned for many years.