For me, the nickname "Frankenstein" here makes sense for the 15" wheels (from a '85-'90 R107 or W126?)!
I really don't like this kind of aesthetic "tuning" or "custom" in a classic car as the Pagoda... The superb original design from Paul Bracq shouldn't be altered. Mercedes-Benz cars are usually so perfect, so balanced, that if you change some part of the factory design, the risk to destroy their elegance is very high.
At least the 6.3 engine has the same age of the car, and this "experiment" was even tested by MB, as Richard said.
As the sedan W109 6.3, the charm of the factory 280 SL 6.3 precisely was that it had a look very close to the standard 280 SL: only a slightly modified bonnet and wider tyres.
Regards,
Albert de la Torre Chavalera
Barcelona (Catalunya/Spain)
Feb.'64 230 SL Euro 113042-10-002432