I don't about all manifolds, but if I mounted my carbs in reverse, the air cleaner would hit the export brace, not only that, but I'd have to use the funky, cross-over linkage. I do know that different manifold manufacturers have mounted carbs sideways, backwards and diagonally to fit whatever airflow theory is prevalent for the period. What I do know is multiple carb intakes may not be the most effecient thing for the street, but with a little effort and some tuning, they work just fine. I get a laugh from people claiming they can't get their carbs to stay in tune on mulit-carb setups. Why? do the mixture screws vibrate loose? Are there evil forces at work? If it's right to start with, it's right. I'd put thousands of miles on street bikes with four carbs and never, ever had the carbs give me trouble. The trouble starts when people that don't know what they're doing start messing with things they don't understand. It doesn't matter if it's one carb or two, if you don't know what you're doing you can make a mess of it in a hurry. One final note: I think a stout ignition is ESSENTIAL to any carbed car, and especially so with multi carb setups. If you're still running points, you're just asking for headaches.