750 on a 318

It's already too big of a carb for a basically stock 318, but the mechanical secondaries will make it even worse. You might end up spending a bunch just trying to tune it because you'll likely need a variety of jets, squirters and pump cams to experiment with. If you don't have a choice, I'd somehow try to safely disable/disconnect the secondaries alltogether. Jetting a big carb leaner may create a very big lean bog when you hit the gas!