Memphis
Husqvarna
You will likely need to remove the cylinder head and measure the bore to settle the displacement issue. With a Husqvarna that old it has been rebuilt and repaired several times. Because of a lot of interchangable parts on Husqvarnas the engine number may not be a good indicator if the cases were changed out to a set from a different model like a 400 or even a 250 if the older 250 cases happen to have the same reduction web my 82 250s have. The inner web can be removed and allow the use of the big bore cranks. Husqvarna being a small manufacturer at that time did not make specific engine cases for each displacement. The castings from the 5 speed 250 are the same for the larger models with only application specific machining operations applied
..I'll pop the engine out of frame and remove the cylinder head this afternoon :-) Will post details in mo..