A few options for you:
1) swap lower cases with a 400 engine, no oil pressure readings or light though.
2) drill and tap the existing case oil port holes to accept pipe fittings for running braided hoses to an oil cooler you mount somewhere. no oil pressure light or readings
3) block the oil ports using this piece so you keep the oil pressure switch so you have full circulation w/o a cooler and maintain the oil pressure light. Not 100% positive this piece fits but pretty sure.
1) swap lower cases with a 400 engine, no oil pressure readings or light though.
2) drill and tap the existing case oil port holes to accept pipe fittings for running braided hoses to an oil cooler you mount somewhere. no oil pressure light or readings
3) block the oil ports using this piece so you keep the oil pressure switch so you have full circulation w/o a cooler and maintain the oil pressure light. Not 100% positive this piece fits but pretty sure.