Garage Cabinets, Garage Storage, and Garage Organization

Hi, I am new to the forum, so I hope this is in the right spot.  I have an Australian 4.5L V8 Mercedes 450 SEL, 1975.

I am putting the head back onto a car I have recently bought.  It came with the head off and the previous guy did not mark the timing chain or cam shaft sprockets.  

Despite buying several Mercedes books, none of them show what the timing marks look like.  A search of the web has not helped me either.  Can any of you tell me how to align it?  There is the key slot on each cam sprocket, but otherwise no obvious or even unobvious marks on the sprockets.  There are a few possible marks on the camshaft bearing, but I am not sure whether they are what I am looking for.

I have the crack shaft on TDC and the cam shaft with the key slot at about 10.00 O'clock, but when I turn it by hand it comes up hard (I guess a piston against an open valve).  I haven't yet got to the other camshaft...

Please help.

Regards,  Erik from Oz