Need Some Input

Hey guys. I have been doing a bit of research and am still undecided of what to do. I am currently looking for a small block engine. Want to go 360 LA or Magnum. Surprisingly where I'm at its slim pickings from the scrap yards and if they do have a motor its got 120k and they want 700 bucks for it. Also I have a hard time paying for something that doesn't come with a warranty. Especially if I can only take the guys word for it after he gives me a jack-o'-lantern smile. So I figured I could look online and find an engine already assembled. Started searching....and searching....and searching and everything is either for a Chevy or Ford or the price is outrageous like 5k for an engine. I do have a mechanical background mostly with motorcycles so I do have some of the tools to assemble an engine. Possibly thinking about getting a short block and building from there. I have a 318 that I can use parts from so that could save some money if I am convinced I should build a short block. My budget is about 2500 and this motor will be going into my 72 dodge dart. Car is for street use only weekend driver. Any one with any leads or suggestions let me know what you think.