Show a picture of how you connected the bulb on the back. If it is reverseable it is not sacrilege, just a momentary lapse of reasoning. If you drilled the metal........Welcome to the Forum...Doug
My, Doug... You didn't tell us you were a diplomat

Well put.
Honestly, though, during the 50s to 70s, many a valuable phone was destroyed by conversion to lamps, and that is why converting will make collectors shudder.
However as Doug says if it is done without destroying the integrity of the phone via brackets held by existing bolts, and the phone can be reverted eventually to its original state, it is ok, I guess
Some past conversions used the switch of the candlestick to switch the 120 volts - not a good idea. If it doesn't destroy the switch as it isn't designed for that voltage and current, it is at very least a serious shock hazard. Better to use an properly insulated and voltage rated external in-line switch and keep the cord free from the phone itself. An option would be to use a socket with a built-in switch. This would be my greatest concern.
Just make sure it doesn't destroy a rare telephone. One has to think that the phone might not always be in your family, so a thoughtful conversion if necessary is your best bet.
Don't get frustrated! It does look nice.
Dave