Here's a more philosophical answer. Do you enjoy driving the car as it is. If the answer is "yes," why would you want to trade certainty for uncertainty. There's a reason that the brain box for the high-compression engines is a different part number than for the later models...same with the manifold pressure sensor. Let's face it, our 1800s may have been performance cars 30 years ago, but the Dodge Neon rental I drove recently will out-handle and out-perform my '70E, despite the previous owner's addition of a big bore kit AND an agressive cam. Me, I wish I had an engine like yours that idles smoothly and goes a decent interval between fill-ups of high-test. There's so much more involved in owning and driving an 1800 than the engine; if it ain't broke, I sure wouldn't try to fix it.