Oh, I wasn't fretting about the snapped dipstick, I was fretting about the garage's attempts to remove it dropping plastic into the sump - or the metal!
I like sunroofs, though. Main reason I sought this car out - wanted the sunroof and V8. But the sunroof needs fuse 44 pulling, from a forum search (though the way it stops at the halfway is very solid, it's very much a "STOPPED!"). If that doesn't work, well, then I'll get a dealer to prod it.
Here's my 300's face:
I see screws in the numberplate. I see references elsewhere to the plinth fitting into the grille. So... screws into my bumper, or screws into a lower mounting for a plate plinth? Guess the eggcrate will fit regardless!