Damn, didn't see this. The hot ticket right now for the 409 is K1's forged steel crankshafts (PN 346-4000RB6F-24, $780) It' a 4" stroke. On a 4.030 bore nets a 408, some call it a 409. My math comes out to 405.139 but deck height could come into play adding a little more volume. Either way..... that's a crank.
Check this write up out. Real dyno results with NEW parts.
http://www.gmhightechperformance.com/tech/0908gmhtp_lq9_408_stroker_budget_build/viewall.html
Here's another on a budget using a SCAT crank, again with dyno results.
http://www.popularhotrodding.com/tech/1201phr_409ci_lq4_iron_block_ls/viewall.html