Need help. Tax times Transit 2.4 TDCI

Good evening. I urgently need your help. A transit 2.4 TDCI 100 HP from 2007 gets a new engine and only the block does not have a complete engine. I have already almost disassembled the engine and don’t understand it with the control times. I have never done anything like this before. In the description there is always talk of 50 degrees before OT where you should plug the adjusting pin in…..why 50 degrees before OT ??? On the flywheel is a place of about 5 cm where the teeth are missing, but the Sti ft fits between every tooth? The camshaft wheels have file for the OT make-up, but how can you just adjust it later. It’s the speeches of any make-up on the flywheel itself, measure the circumference of the flywheel etc. to determine the 50 degrees before and the OT make-up, I somehow don’t understand anything. I had to change before the engine block and install it again in the car without the head etc., because I didn’t have the gearbox removed (engine with crane removed from the gearbox) and then to install the head and everything else again. When the head is back on it I wanted to install the control chain etc. But how can I manage this with the control times. Somehow I don’t think the description in Etis is quite right, because the fuel punch has a make-up (with 6mm drill bits) but how does it stand doesn’t matter or? Is a high-pressure pump. Just don’t understand how I should adjust OT on the crankshaft, because the E instellstift somehow blocked in every tooth. I am going crazy. Can someone give me a hand?