Well to take a step or two back: First on the steerer length, that 240 mm does sound kind of long for a threaded fork. You can confirm by measuring the the head tube which is probably somewhere around 160-170 mm. You then add the space that the headset will take up on the fork steerer (called the stack height). This will be the width of the cups at top and bottom of head tube, the nut at the top, the lock ring, and the threaded portion that adjusts to the top bearing. The 40 mm estimate provided above is a good one. It is better to err a few mm too long than too short; that can be taken up with spacers.

Threadless forks have longer steerers to accommodate the stem.

Secondly, as noted above, don’t worry too much on Italian vs English threaded. It’s a big deal for bottom brackets but not as much for fork.

Lastly, you want to make sure of the crown race diameter. 26.4 mm is the standard on most bikes from that era. 27.0 mm is a JIS standard you will come across sometimes. Do you have the crown race from your headset to measure?