440 low profile roots style manifold

There are 3/4 inch aluminum adapter plates available on eBay for around $100 that adapt low profile dual fours to superchargers, but I would be wary about flex in the casting of a conventional manifold. If you look at most B-R/B blower intakes they are manufactured to catch the china walls on the end of the block. A 6-71 or similar blower takes around 100 hp to drive at full load. Supercharger mounting surfaces need to be rigid and flat and true to within .004 of an inch, confirmed with a machinists quality straight edge and feeler gauges, after the intake is torqued down. You may want to check out Weinle MotorSports for some ideas. I think it may be possible to get enough aluminum plate to weld up a conventional manifold to eliminate the factory valley tray by meeting the top end flanges of the block and join up to a prefabbed adapter plate, but I would add some serious (at least 5/16 aluminum plate) bracing in any place I could find to put it.