360 LA engine crank no start

I have a freshly rebuilt engine and I’ve been trying to find a reason why it’s not starting tried everything that’s on all the forums about ignition timing and spark and fuel I don’t know what else could be wrong but if I’m missing something please let me know i am kind of a beginner with this so any help or tips will be appreciated also for some reason I have to jump my starter to start it when I try to start it with the key the starter just clicks had a short when I first connected the starter which caused the whole car to lose power fixed that but still have that problem