Let's examine a famous dead end: "de-stroking for more power". This actually worked when the only heads available were terrible.
When the heads improved, the shorter stroke required a longer rod to avoid high piston weight. So, as displacement (and vacuum) went down, the rod ratio went up, producing an engine with 1% higher peak power, and no torque.

The first question should be "how well does head flow match the existing package?".