Thanks for all the good replies.

To answer the questions:

It's a 383. I've never raced this and I don't drive it hard at all. It's a nice clean cruiser, something to take to shows.

Really, because I don't drive it much nor race it, is why it's lasted so long in its current condition. It's just that when I most recently took it out for a drive I kept asking myself "what if it had better pickup, what if I tightened up the steering, etc". I've never even taken off the heads the whole time I've had the car.