OM 603 960 TIMING HELP

[ALBERTO]

Hi To everybody
I need your help please as I am doing head gasket and some other major rebuild but I have some problem concerning timing OT.
In my car a w 124 300 D Turbo 1992 I can found OT but the indicator is some kind of BRACKET bolted on the engine and this is adjustable.
I unfortunately unbolted it and discovered after it was adjustable so now before move the engine I would like to block in good position.
Is there other fixed way to see OT ?
I saw some kind of HOLE in face of OT on the block may be I can use this but I am not sure.
Thanks a lot
Alberto