Can you post a picture of that motor? Where did you get that number? Using Mercury Marine, it comes back invalid.
Like I said, if you can post a picture as well as where you are located, it would help, there are variances if you are in the US or out of the country.
After searching a bit more, the serial number 2504091 comes back to a 1967-1969 Merc 650 65 HP model. The serial number range is 2119749 thru 2803561
I looked it up on oldmercs.com, maxrules did not have that number listed in their charts, but I can tell you, if it is a read band hood on it, that is about the range for it, I have had several red bands. But you never know if the hood has been changed.