I think 600hp (at the crank) can be quite streetable and reliable given the build-ups I've seen and read about. Mine is no trophy winner by any means, but the build is simple: stock longblock, bolt-ons and a power adder. Given the numbers my combo put down (on a load bearing chassis dyno that reads slightly lower than Mustang dyno) it's probably making just under 500hp at the crank. Street manners are great too; it idles and drives with stock-like characteristics, cold AC, power steering, windows, brakes locks and cruise control.
As far as reliability goes, that'll depending on tuning, no matter what type of build it is. One thing I can't calculate accurately is fuel mileage...i simply can't keep my foot out of the throttle.