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well thats what i mean,we can buy cheap for both,like cast cranks etc etc.. its all relative to make 500 isnt really that tuff anymore for either bb or sb.. im giving up its to hot.

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The "econo" route isn't bad at all, but... there's a term called RELIABILITY when selecting parts for the assembly of a 550-600 hp motor (whether BB or SB). You must insure that the motor
will make the 550-600hp, reliabily. A member previously posted about stress on the an engine at about 960 hp. That's true, and you would need NEARLY the BEST parts that money can buy for that power level and beyond. However, 550-600 hp does put SOME stress on the internals (reciprocating assembly) and at this level you NEED a bit more than you would at the 500 hp level. MORE than
a "warmed over" Magnum motor (400-450 hp, BB or SB) would need. Think about stress on crank/rod/piston assembilies, and at every 1000rpms (over 5500 rpms) the force keeps increasing itself, squared (check on this).
So much more factors come into play when increasing power. Big Blocks are more TORQUE productive
than Small Blocks and build it STRONG, FROM above idle going thru the midrange rpms. The bigger block design contributes to this, but they are victims to excessive bobweight. Rev potential (NOT hp) is less in the Big Block. The Small Blocks' claim to fame IS the fact of lesser bobweight and with that comes BETTER rev potential (more hp/torque upstairs, equipment depending) with increased "breathing" capability. But
their downside is LESS torque (than the Big Block) in the lower ranges. That's why Small Blocks NEED more multiplication (gears) than the Big Block.