340 not running anymore...Help Please?

Ok, there are 4 basic things you need to run, Compression, timing, fuel, and spark. at the point your at, you need to back up, and start from scratch.
First things first. Buy a cheap compressionn tester. you should be able to find a crappy one for under $20 that will suffice for this. Check your compression on all 8 cylinders, write down the numbers and post them here. If you can keep it running long enough with some fresh plugs, put a timing light on it, and give us those numbers too. You can also get cheap inline spark testers. Plug it in on each wire and make sure that you have a strong BLUE spark on ALL wires. Fuel, we'll get to it later. For now, that's your home work!
I want to tell you how sorry I am about your troubles. I REALLY feel for you! I just got back from my second tour in Iraq and decided to buy my highschool dream car, a 1974 duster. I paid a little more for the car because EVERYTHING was suposed to have been redone less than 10,000 miles ago (engine,trans,wiring,ect...) On the way home the steering gear box snapped, two weeks later the tranny blew, I had to pull the manifolds to drop thr tranny, when I did, I found out that the bums had rebuilt cracked heads. I'm a blue color family man, this hurt. I sucked it up, bought a new preformance tranny and a set of ported high compression heads. I fired it up, and the new found compression grenaded the bottom end!
I feel your pain!