Most inverted problems are related to incorrect tank height (too high). That can't be helped in many airframes, so other "fixes" have to be applied -- such as on-board glo systems, idle-bar plugs, hotter plugs, higher idle speed. However, a properly tuned engine should run just fine inverted, following start-up (that can be the difficult bit).

The low end needs to be a little bit leaner in an inverted set-up with a high tank mount, than it would normally be with a 90 deg or upright config. This creates its own problems, such as part-throttle lean-out in inverted flight.

The real fix is to get the tank height correct.