Dyno'ed My 360..it's a pig..what next?
What is your budget?
You can't get better advice than from ABODIES only...the only trick is to figure out which one you can afford/do yourself or pay someone to do it for you. If you had $5000 -$8000 to spend and you were looking to get closer to 380-450HP, I would recommend you pull your motor, and send it to MRL performance or Indy Cylnder Head (or someone that really knows MOPARS). I really like what MRL Performance recommend (new cam, aluminum heads, valves, lifters, intake, new carb MSD ignition etc). Let them do what they do best...build awesome motors. If I had to do it all over again, I would have paid $10,000 to MRL performance to build me a 500HP motor from scratch the right way rather than let the hack job idiot that I used locally try and do it for me. (he was trying to put LA heads on a Magnum Block and couldn't figure out why he kept bending pushrods and valves). I spent $5000 on parts (block, heads, valves, cam, etc) ended up having to ship my motor to INDY Cylinder Head to have them tear it all down and start over and fix the problems. (that cost me another $5000). So I am $10,000 into my motor. I could have had one BAD A$$ motor from MRL for $10,000!
IF you dont have that kind of cash, I agree with everyone else, pull the engine, start with the cam shaft, have your iron heads tuned, new high performance v build the rest of the motor around the cam. It really is the heart of the engine.
Now I don't know everything, and again, I AM NOT A MECHANIC...most of these guys on FABO have forgotten more than I will ever know..but from a lay person (a customer who says please build me a sweet engine) I have learned the hard way...I would have been better off to have it built by a professional shop.
Good luck..send us some before and after pics..and tell us how it goes!