A more powerful Swordfish engine carries production costs

Would re-engining the Swordfish with a more powerful Mercury or Perseus be worthwhile?

It is technically possible, but redesign time and scarce engines could make the production penalty greater than the performance gain.

Engine choice was an industrial decision rather than a free performance upgrade. A more powerful engine would require airframe changes to preserve stability and useful load. Those changes would interrupt a mature production line at the moment quantity mattered. The historical engine choice also reflected availability, even though it was not the Fleet Air Arm's ideal power plant.