Borderline red

[ctmv20]

I had a 1988 135hp merc with a similar rectifier setup and no voltage regulator and the voltage would run up as high as 16V. I was worried that it would mess with the electronics but it never did. Researched it at the time and found out that it is normal for those years with no regulator. For fun I retrofitted a voltage regulator from a later model by following some internet instruction and it kept the voltage around 14V. You should be fine leaving it as is.