You didn't say exactly why the new fuel line was wrong but this may help you figure out which engine and one reason for the wrong line. The 250 engine has the fuel pump located between the distributer and the right motor mount. The 292 engine has the fuel pump and motor mount positions the other way around. Therefore one fuel line would be approximately 4 inches longer than the other and this would be on the fuel pump end. Also the 292 pre bent line would be about 2 inches taller from the pump fitting to the carb fitting.
Another quick check instead of using casting numbers is the height of the lifter side covers. The 292 covers are approx 6 inches tall and the smaller displacement engines are all the same size at approximately 4 inches tall.
Neither of these visual clues will tell more than if the engine is a 292 or it isn't. To know exactly the specific engine and its original use you will have to check the casting, date, and serial numbers.
Hope this was some help to you.
