The Power Adder SBC Short Block comes standard with many features designed to handle high horsepower levels (Turbo, Blower, Nitrous)
The Dual 3/16" Keyway option is highly recommended for supercharger applications.
The ATI Blower Balancer has both the 3 bolt SBC pattern and the standard 2.80" Chrysler Blower Bolt Pattern & extra thick BBC Hub. 
The ATI Balancer requires a matching ATI Timing Cover which accepts a BBC timing cover seal to match the Balancer's larger hub.

383" Specs:
Block: Smeding Heavy Duty 4 Bolt Mains, 9.025" Deck Height, 1 Piece Seal, 4.000" Bore
Crankshaft: Smeding 4340 Forged Steel, Internal/External Balance, 3.800” Stroke
Rods: Smeding 4340 Forged Steel H-Beam with 7/16" Bolts, 5.700" Length
Pistons: Forged 2618 High Strength Aluminum, Coated Skirts
Rings: Plasma-Moly Top, Low Friction Oil, 5/64” x 5/64” x 3/16”
Rocker Arms: Smeding 1.5 Ratio, Full-Roller
Cylinder Heads: Smeding Aluminum, 180cc Intake Port, 2.02"/1.60" Valves, 65cc Chambers
Head Gaskets: Cometic Multi-Layer-Steel
Head Fasteners: ARP Head Fastener Kit

406" Specs:
Block: Smeding Heavy Duty 4 Bolt Mains, 9.025" Deck Height, 1 Piece Seal, 4.125" Bore
Crankshaft: Smeding 4340 Forged Steel, Internal/External Balance, 3.800" Stroke
Rods: Smeding 4340 Forged Steel H-Beam with 7/16" Bolts, 5.700" Length
Pistons: Forged 2618 High Strength Aluminum, Coated Skirts
Rings: Plasma-Moly Top, Low Friction Oil, 1/16" x 1/16" x 3/16"
Rocker Arms: Smeding 1.5 Ratio, Full-Roller
Cylinder Heads: Smeding Aluminum, 195cc Intake Port, 2.02”/1.60” Valves, 65cc Chambers
Head Gaskets: Cometic Multi-Layer-Steel
Head Fasteners: ARP Head Fastener Kit

Cam Specs:
Extreme: .510”/.521” Lift, 231°/236° Duration @ .050”, 111 LSA
Eliminator: .544”/.543” Lift, 236°/244° Duration @ .050”, 110 LSA
Mighty Mouse: .549”/.546” Lift, 242°/250° Duration @ .050”, 110 LSA

Torque Converter: 2,400-2,800 Stall w/ Extreme Cam, 2,600-3,000 Stall w/ Eliminator Cam Required