I think i addressed that in my post, 550 is a 'comfortably attainable' target and probably the best for $$$ per HP comparison.

All in all, the stroker shortblocks are going to be about the same cost, again the difference is in the heads....an OOTB Edelbrock BB and SB (for sake of comparison) cost about the same too, but the BB flows enough to make 550HP, the small block really does not....not without about $1000.00 worth of porting and maybe 200.00 or so for higher rate springs/retainers in order for the smallblock to attain the RPM high enough to flow the air needed for 550hp. You can probably/MAYBE make near 550HP with a hydraulic flat tappet cam in a 408, but that would take a lot more porting and in the end it wouldn't be the way I'd go....by comparison I know it's almost rediculously easy to make 550 with a juicer in an E-head soundly machined Big Block.

Stock stroke, you can certainly get a 340-360 to the 550 range, again thast's with enough head and RPM but I think it'll cost you more, certainly more than a 440 based motor would at the same power level.

Additionally, you can't bring the A motor/A body to B motor/B Body into the equation, to compare fairly it would have to be inthe same vehicle with the only difference being the drivetrain weight itself The small block would have an advantage there in that you can run a much lighter/less power robbing 904 behind one, if it's suitably built. So Again to be fair (if that's what we're really after, not personal preference/bias after all ), it'd be best to back them both with 727's.