I have had a lot of miles of fun in a 427 425 hp Chevelle. It seems to be one of those happy combinations that performs better than it should. That engine in your car would be quite a sleeper. With little more than a cam change, headers and tuning, the 390 hp 427 can perform pretty well too. Here in Ontario, you need all the applicable smog equipment to keep the MOE guys happy and that can be a bit of a challenge.