Add on one what?
What do you mean is it inevitable? If you want to tear into a magnum, I can’t change is all you’re really going to need. It is already a 9.0-1 engine.
Actually, from where you stand, you can simply copy one of Mopar‘s crate engines.
A good way to go about building a magnum from a good core would be to;
Use a Edelbrock RPM intake, 650 cfm carb, (Holley or Edelbrock) headers and 2-1/2 exhaust, electronic distributor and a cam that suites the need. Use a cam car er 216/218 duration @.050 and you may want to restall your converter. Hughes has cam & tappet packages along with there springs. A new timing chain and tensioner would be good as well.
