GEN light staying on when key is off

[Fnixon]

To me it sounds like the cutout relay points failed to open and I would think the new regulator is bad. You may have a damaged generator now.

Here is a further explanation that I think will explain what you observed. When the engine stops, the points in the ignition will either be open or closed. When it stops with the points open, the GEN light is powered from the stuck cutout relay in the regulator and the current flows down through the light and through the oil pressure warning light. Thus yo see both lights on. However, when the points are closed, the current goes through the GEN light and down through the coil, through the points to ground. Because the GEN light has a very high impedance, the voltage at the coil is very small and the oil pressure light does not light up.