Theres way more to it than when does it knock. Whats on it for heads, rods, pistons, and crank all dictate the boost limit not knock. The injector size will determine the amount of fuel available which will determine the amount of air that can be run through the motor before experiencing knock. Don't forget timing either
Why did he stick with the 305 instead of a 350? What tranny and can it even handle a boosted motor?