Yes, I’ve a 211 E55K that has been running on LPG for over five years now. Has the same sort of engine as yours - an M113 V8, but with a supercharger.
Runs smooth as silk, has plenty of power - most people would struggle to tell any difference in the real world.
Have you any details on the LPG installation? Either type of system or who fitted it etc?
What type/size tank does it have? If it’s a toroidal tank located in the spare wheel well it won’t use any luggage space at all
A decent install should run the same on either fuel, with seamless switchover etc.
As said spec wise it looks like a decent one. Regards the history - I’m guessing you’re trying to look up the British MOT history? It’s on NI plates, so if it’s been used over there they have a different type of test that does not show up on the MOT history checker.
Plate checks out with the DVLA and they have it registered for dual fuels. The data card also shows it was a UK supplied car so I don’t think you’ll find it was registered elsewhere.
Good luck