14045445 is probably the most common casting Chevy made. Should be fine, unless you go very far over that "700hp minimum". 650 - 700hp is about what most recommend at the high end for a 2-bolt production block. Yours is a passenger block, not a tall deck. You have what you need.
Heads are peanut ports, great for a heavy tow truck but not good on a higher revving ProStreet rig. If you plan to spend most of your time on the street, find some castings that end in -781 or -049. They're large ovals, open chamber, should be easy to find.
A factory cast crank ain't going to live for long at that power level, either. Try to find a factory forged crank, or go aftermarket.
Those look like "thumb" rods - is the scallop on the sides round at the big end or shaped more like a "Y"? If round, they're "thumb" rods, strongest OEM rod that used 3/8" rod bolts. Even with aftermarket bolts, your 700hp is about the limit for those.
Don't shoot for a specific power level. Build something that's streetable (pump gas with a rough idle but still isn't a pain with heel-toe driving to keep it idling) and affordable (OEM heads, reconditioned rods, forged crank) and regardless of what a dyno says, you'll have something that'll shred tires and push your eyeballs toward the back of your skull.
When you've grown tired of that, snag an aftermarket block, stroker crank and aftermarket heads and try your luck with a 540 or bigger mill. Enjoy limited traction with your current build, though, 'cause there won't be any at all with the big engine.
IF you're considering a stroker, there's a Scat cast one that comes up pretty much weekly on ebay. It's in Florida with a $250 opening bid, $275 buy-it-now, free shipping. It'll take +.250 rods, can't use stock length, but good Scats can be had for around $300. The .250 longer stroke will make you a believer in longer stroked engines
