A big part of the reason for the knock sensor is to control knock that can occur with sudden application of WOT at cruise or low speed when the EFI is running the engine lean. The computer dials in spark advance to ignite the lean part throttle mixture. Lean mixtures are harder to ignite and so use more spark advance.Full throttle application can not use as much advance so the knock sensor works with the computer to take out spark advance to keep the engine in one piece.
The old days a vacuum advance distributor would sense the drop in vacuum from sudden application of WOT and reduce spark advance accordingly, but the engine could still ping or worse detonate.The knock sensor prevents this so the spark advance can be optimized.

They don't like automotive discussions here so I'll leave it at that, I just want to help you get your conversion sorted out.