Sounds like you put the timing 180 degrees out. It would not have been running if it was initially 180 out. I can give you some information on how to reset it if you want but it is going to require a bit on your part. The firing order is 18436572. Cylinders 1,3,5 and 7 are on the drivers side of the engine from front to back. The passenger side is 2, 4, 6, and 8 from front to back. The best way to do this is to remove the valve cover from the drivers side. It is best to use a 5/8 socket and large ratchet, put it on the bolt in the center of the harmonic balancer on the lower pulley and turn the engine clockwise as you are looking at it from the front. The intake valve for the #1 cylinder is the second one from the front on the drivers side of the engine.
While watching the intake valve on #1 cylinder, turn the engine clockwise and watch for the intake valve rocker arm to go down and begin to start back up. as it nears the top, watch for the timing marks on the balancer to come into view. Once you see them coming around, quit turning the engine when the timing marks align at TDC and with the distributor cap off, look for the distributor rotor to be pointing somewhere close to the #1 wire on the distributor cap. The #1 position on the cap should be somewhere to the front of the engine just slightly to the passenger side, usually pointing toward the front corner of the passenger side valve cover, or thereabouts. If it is pointing to the rear of the engine, it is probably 180 degrees out of time. After turning the engine clock-wise and aligning the marks you can re-install the drivers side valve cover.
The way I prefer to do it myself, is to stop turning the engine at about 12-14 degrees before top dead center on the timing marks. With the distributor pointing toward where the #1 should be and the distributor cap ON, install a spark plug in the wire of the number one spark plug wire, lay it on the engine (grounded) where you can see it and with the distributor very loose, and turned toward the far passenger side of the engine and the ignition ON, rotate the distributor COUNTER-CLOCKWISE while watching for the spark plug to fire, and the instant it fires stop and lock the distributor down, or snug it up. You may have to turn it COUNTER-CLOCK-WISE fairly fast to begin with, possibly several times while taking note about where it fires the spark plug. If it fires, do it a bit slower each time until you are able to stop it just as the plug fires.
Once the plug fires, lock the distributor down, re-install the wire on the #1 cylinder and the engine is ready to start. Keep in mind that when running, the distributor rotor is turning clockwise. I have done it this way for so many years that once it is done, I never have to recheck the timing after it starts because I know it is going to be right. This requires a certain "feel" and with enough practice it becomes second nature.
If the engine was running, what ever made you think it was 180 degrees out? If it was 180 out there is no way it could do anything but pop and blow fire out the carburetor. Now, a good word: Depending on who installed the distributor and wires, they could have made the number 1 position anywhere. On the old point-style distributor, the #1 position on the cap was pointing toward the drivers front corner of the valve cover. With the HEI, it was changed and the rotor pointed toward the front corner of the passenger side valve cover. Now, pay attention: Regardless to where the distributor is pointing when the timing marks are aligned to fire the #1 cylinder, wherever the distributor is pointing at that time can be made to fire the number one cylinder by changing the spark plug wires. This is not the correct way to do this. With the marks aligned, the rotor should be pointing somewhere toward the front passenger side valve cover, or thereabouts.
I hope I haven't confused you because I have almost confused myself (LOL). This all comes with experience.
