Yeah, definately check your oil pressure and make sure its is up before you fire it up - could be why its is not turning over real easy, lack of lubrication. This is just safe-guard to ensure everything has oil (and that the oil pump has been assembled correctly!) Know this may sound obvious but have you checked your ignition fuse(s) maybe blewn when re-connecting everything?
Good Luck - you will get it going and I bet it's something easy - always has been for me anyhow.