2K after you buy the engine? Put Stealths, Edelbrocks, or Trick Flows on it and a 240ish@.050 hydraulic that works with stock rockers, Eddy RPM intake, headers. It'll make 400 horse. 3000 stall and decent gears and it will haul.

If you can find stock pistons out of an early engine cheap just swing them in and go. They pop up from time to time.

There is a 400 with a 440 crank in it in the classifieds here for $1200 bucks, looks like a good motor, seller advises going through it. Check it out.

I'd go with that engine that ran 12.16 for 2K. Really, you're not going to build a fresh engine that will run anywhere near that fast for less than 4K if you include purchase of a core (unless you get a lot of good deals on used parts).

If you're not too used to tricked out big blocks that 12.16 will really impress you IMO.