Looking at the EWD for both 96 FZJ 80 as well as 97 LX450, the oil pressure sender is not wired up to the ECU. It is wired directly to the combination meter. I can't see how the ECU could make use of the signal without being wired up to it. It shouldn't be a problem to drop the OEM sender, the gauge in the cluster just won't have a reading.
Good to know. I'm not so worried about the cluster not having a reading because it was never very accurate anyway. I will probably hook up the dash warning (idiot) light anyway to the aftermarket sensor since it will have a "WK" terminal available. The new sensor will push actual usable data to my PLX and be displayed my DM6 gauge and/or my tablet.
I am however thinking about leaving the brand new sensor in its original place and maybe getting an additional Tee fitting to run both OEM and Aftermarket on Joey's PeaceTee. depending if there's enough room to clock that much crap in one location. Otherwise I'm also looking into maybe running a sandwich plate so i can add the new aftermarket oil pressure sensor there instead. It'll be closer to the firewall for routing the new wires to the monitoring module.