371 build W/Big Mouth heads

I'm about to embark on a 371 (.060" 360) build with the vaunted Hughes CNC machined Edelbrock Big-Mouth heads. I say vaunted because they were VERY disappointing on the flow bench if I'm looking at flow rates and the numbers themselves. I still do not understand why Hughes completely removes the shortside on these heads. I will post the full flow chart later but the heads flowed a peak of 284-285 cfm with a lot of "help".

371 .060 Icon flat tops. 10.8-11.0 comp
Eagle steel 3.58 w/Armour shield
Scat 6.123 I-beams
Total Seal gapless top 1/16"-3/16" ring pack
Eddy BigMouse heads 63 cc chambers 2.08/1.6
Eddy SuperVictor intake ported
Hughes .350" offset rockers 1.6/1.6
Big bad custom Comp cam solid flat nitrided 251/255 106 .600"

This will be tested in the next two-three weeks. I really don't want to bad mouth the big mouths until I know because even with 280+cfm they may produce serious power. I've done 2.27 HP/cfm with Edelbrock castings before so who knows? I'm looking for well over 500 HP @ 6800 rpm+ to consider this build a success. What say FABO?