If i find the pictures from a dodge D50 do you want me to send them to you?
The picture is kind of hard to say for sure, I am going to see if I can locate another picture. It does appear the marks are on the gears. Make sure the piston is at top dead center on the compression stroke. Both valves will be closed on the compression stroke.
If you set the number 1 pistion to top dead center, both valves closed the keyways
should be in the right postion. Look at the marks on the gears and put the chain on the marks with the plated chain. Install with the marks off to the right side like the pictures.
ASE Certified Technician
California smog licensed, ASE ceritied in L1, A6, A8 for over 30 years professionally