Your goals don't seem to be too far out at all to me. 350-400 horse in a SBF is VERY doable with the right parts.
If your looking for a 90% street car that will finish the 1/4 at 100mph, I would save the $$ you'd spend on that aluminum block, and get a nice pair of 185-195cc aluminum heads (Canfield, TFS, AFR ect.), and put them on a good strong bottom end with some forged flat tops, a good intake like the Weiand Stealth, a good cam selection (I hear GREAT things about Jay Allen at Camshaft Innovations), 600 - 650cfm carb, long tube headers, a strong tranny with some stall, a little gear and you should be pretty much in the ballpark for what your looking for.
Don't get me wrong, that looks like a great block. I guess it comes down to the limits of your budget.