Lockheed had all the design parameters and design flight characteristics of the aircraft. While their conclusions may match your findings, you both have a significant stake in trying to prove that neither the aircraft nor the flight crew were inherently at fault. Lockheed would be particularly keen to eliminate any suggestion that the aircraft was inherently unsafe and to a certain extent it would have been ideal from their point of view if mishandling of the emergency by the flight crew was contributory to the crash.
The accident investigators on the other hand were required to consider all possibilities and not just the ones that conveniently fitted a certain conclusion. While they might have to accept the findings of Lockheed's engineers, they would certainly treat that information with suspicion, because of vested interests in the company.
The fault in the aileron rigging was clearly something that needed to be addressed, but it exonerated Lockheed from direct responsibility for the accident.
The most common finding of pilot error could not be attributed to this accident either, because the aircraft became uncontrollable once it left the ground since the ailerons did not function as they were effectively disconnected from the flight controls. It certainly seems that some attempt was made to discredit the pilots by suggestions that the autopilot controls could have been used to control the aircraft. Had the autopilot not been flagged inoperative and the breakers pulled, I have a strong suspicion that this would have been the finding of the investigation. Such a finding would have been grossly unjust given the time constraints the crew had to find a solution to the problem, it is unlikely that such action to regain control would have been considered in the time available.
I am inclined to believe that the aircraft struck the embankment at an angle greater than 35° of bank, possibly as much as 60°, but certainly a lot less than wings vertical. The flatter angle of 35° would, I think, have resulted in a less damaging impact with the ground and perhaps the possibilty of some survivors. The damage to the aircraft points towards a much heavier impact with the ground which is why I theorise a steeper angle of bank on impact with the railway embankment. I am aware of course of your arguments for the shallower angle of bank supported by ground and other witness marks.
As to the engine being left on top of the embankment, this would have to have been recorded somewhere in the paperwork. The fact that no statement of any sort record the engine being found there, or moved from there, suggests that whatever was on the embankment, it wasn't the engine.
Because of the solidity and physical inertia of the engine and gearbox, in order for them to be deposited across the railroad tracks without damaging the tracks, the engine would have to have struck the embankment lower down, broken away and lost inertia before bouncing up in the air and landing on the tracks. While there is nothing inherently impossible with this scenario, it would have left hugely obvious marks on the approach side of the embankment and does not fit with the propellor strike marks found across the embankment.
Additionally, there should have been considerably more shrapnel and bits of metal and oil scattered across the tracks, which surely would have been photographed, officially or otherwise. It simply doesn't make sense that the engine ended up lying across the tracks given everything else that has been revealed.