Super job, PWF:
The mudflap jewels with back tabs are simple to remove. (Once you spread the tabs and pull off the metal piece, the jewel isn't even attached.) The ones with bolt backs would be harder but I would think metal snips and pliers would do the trick to get it out of the casing. You'd likely have to file off the lip hidden by the metal to get it to fit in the tiger's forehead.
If you scanned an already modified lion-head, you'd have both options.
Regardless, this is all looking really great. -- BB