Here's my 14755-1 for comparison. All original - also the bezel!
And agree in the above mentioned tell signs - plus the shape of the black inlay must be very concave i.e slope down from inside to outside. Most redone's don't slope down correct, even Aldo's, althrough his are close.
Enjoy your watch. The 1.gen SM300's are really some of Omega's finest designs IMO.
/Kim