Pretty good list but I will add to check your engine vibration damper. If you have the 68 or later style with the rubber ring sandwiched in between and if the outer metal ring has slipped and clocked in a different position. if it's way off you won't find your timing marks even near where they are supposed to be but if it only slipped a little can be hard to detect with a timing light and you will manually have to find tdc on # 1 and check for alignment. The second suspect of the top of my head is the torque converter and if they properly re balanced it after separation and reweld.