Never see things backward
You sure you have the right ECU? Okay lets hope that you have everything, now to the basics. Check your battery, sometimes they just die if sitting too long. Check for sparks if your battery is good. Make sure your timing is not mess up. Double check on your spark plug wires and make sure her firing order is correct. Check your fuse if you haven't already. It's also good to have sufficient coolant, I blew a motor not doing that. Make sure your tension on the belt isn't too tight. Also check if your oil level is sufficient to lube her into action, sometimes if the engine is sitting out for too long its hard to make her run. Hmmm, I cant seem to think of any other things other then vacuum hose now. Im out of ideas now lets just hope its not fuel. Good Luck! Hopefully she pulls through, long live the KA.