If 300 hp in a 914 is your goal and you already own a 3.3 930 engine the biggest challenge will be an exhaust system and intercooler that will fit the mid engine configuration.
It just so happens that I have just such a system. I ran this system back in the 90s in the 914 From Hell and it was the ultimate "E" ticket. If you're interested I have other pictures that I can send you.
