Omega produced the caliber 351 bumper movement from 1949 to 1952, and the serial number places yours around 1951. Those more expert than I will tell you, but that "bowler" crown looks correct for the period.
Yep! I have been looking all over the interweb and that's what I'm seeing. Now I just need to replace the hideous band for a leather one and I'll have a nice vintage bumper! Thank you for the help, any idea what it would be worth?