There is a large dot on the cam gear on a CL175 which maybe the same design given the year similarity too. The T/F mark on the rotor is set to the T mark on the rotor and aligned with the pointer marker on the outer case. The O dot on the cam gear should be at the 12 o'clock position very top of the gear. You then join the cam chain with the master link in the top of the gear area. It doesn't matter if the chain when joined is forward or backward of the top position. You are aligning the O dot mark at 12 o'clock on the top of the cam and the rotor T mark and the pointer marker for correct timing.
Loosen the valve adjusters off completely too if there is resistance from a valve spring, although the cam lobes should be in a neutral position on most of the valves when the O dot is at 12 o'clock.
These two pics show a very close up of the O dot on the side of the top of the cam gear and the master link for the cam chain. The other pic has the pointer marker near the upper left hand hole in the outer case for the T/F mark alignment on the rotor.
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