What has been common experience with NASCAR engines. Primarily 358ci R5P7 engines rated at approx 820 to 830hp. What is best use racing or exotic street? What had to be changed for either situation, cam/springs, oil pump/pan, compression, or what? Seems like excellent cost/hp from a fresh engine, worth it or too much hassle? What is going price for fresh engine, not asking but common buying price??