hum, does the chain not have coloured links that represent where the timing marks are. Quite often as a rule if the crank pulley has a keyway then that is straight up when at TDC. Thats a bit of a do dah you are in. Perhaps you could take an injector out and but a rod down the hole and see where tdc is using that and then set it with a protractor ( you laugh ive seen it done and the engine ran well) but would only work if its direct injection, i.e doesnt go into a combustion chamber.