with only 3k I probably won't even pull the heads, if you do I'd have them milled and use the Mopar steel gaskets to get a little more compression. Right now you are at around 8:1 maybe lower if the fat Fel-Pros were used. Like I and others have mentioned, Cam, Headers, Intake (you have the carb), Good ingnition, Good tune, and you'll have all the tire burning, trunk pulling power you'll need for a cruiser. AND if you back the timing down you can use 87. I had a 73 440 from a Fury cop car. It had over 100k on it. We put new bearings in it, I added a 509 cam (wrong cam I know)a Bee Ess intake, I used the factory thermoquad and headers, that car would boil the tires until I lifted. Doesn't take much.