to design the box you could go Suboofer Enclosures - Fraction to Decimal, Parallel, Series, Port Length and Volume Calculators and you could download winisd to design it and get everything
those BLs powered by the 1500d sundown amp is proven to work put it in a great box and your onna be more then pleased i wanna get into local MECA comps and thats gonna be my setup 2 15 BLs and proably one of the 3000d sundown amps