You're ignoring some basic physics if you think the relationship between stroke and torque is a myth
The "lever" concept was effectively put to sleep by SAE papers about 50 years ago. The extra leverage is almost exactly a cross-over against increased displacement in any engine you would use. In any case 4" stroke vs. 3" stroke isn't 33% more leverage except during part of the cycle (they nearly match during the remainder).
So, what does influence torque other than engine size?
1. static compression ratio (yes, not dynamic ratio, because after the "green line" is reached static = effective), and cylinder pressure varies with ratio (but only by E=(1-1÷R^K-1), where K is usually 1.4.
More compression will also give a different improvement based on what the original ratio was.
However, the frequent comment that "1 point of compression = X%" is simply not true, the change in efficiency doesn't vary with the actual change in ratio increments, or even in percentage change.
Going from 6:1 to 6.6:1 is more effective (+3.6%) than raising 9:1 to 9.9:1 (2.7%) even though the increase is 10% for both, and of course the larger actual change is greater for the higher ratio (.9 vs. .6).
2. volumetric efficiency; at low speeds pretty much anything has its maximum VE (85-95%) unless the cam is either very small (cylinder doesn't fill) or too large (late IVC, low expansion cycle, too much OL)
3. resonant (wave) tuning or inertia fill - both very unlikely in the RPM range you would use
We're left with displacement × CR, and displacement is far more effective (although not as efficient).
