I've often used Helicoils in cast iron in the past. If you can get the right Imperial thread version, a Helicoil will work in this application and will allow you to use an 'original' design stud.....
"Heli-Coil® has the most effective and universally accepted method of thread repair. HeliCoil® quickly, easily and permanently restores stripped, worn or damaged threads to original condition.
HeliCoil® inserts can be used in any material: cast iron, steel, copper, brass, bronze, aluminum, magnesium, plastics and wood. After installation, they never shift, wear or back out. Stripping, fatigue, corrosion, crossthreading and seizing are eliminated."