A megarange may be overkill as far as cage and body length but should work.

You can find derailleurs with claws, those should work fine, I am not sure if there is anything with the Simplex claw that would make it problematic for using it with another derailleur (threading etc on some components were unique backk in the day).

If you don't get a definitive answer here, you can also ask in Classic & Vintage.