I'm running a 74 .060" over block, decked for square, stock heads, Comp cam an springs; cant find the specs but billed as a stock 340/360 unit. Dual exhaust through late(r) model Magnum manifolds. A big block AVS, 600 cfm, I am told, sits on cast iron 273 4bbl intake that has been benchtop machined, (pronounced: hacked) into a single plenum. It was free;it works LOL. No dyno yet but it really woke that 318 up in the Challenger