Re: 1963 65HP mercury
Your engine is before the Thunderbolt CDI (battery fired), which came in 1966 (I believe but could have been 1965) and first unit had points, and then changed to a triger in the 1967 ss model (which I owned), and 1968 and up all models.
All the CDI ignition engines had surface gap spark plugs, (yers had cornventional plugs), and may have had a magneto to fire 'em distributed by the distributor. (Dunno as I never owned one of yer vintage).
Bottom line: get a 1963 distributor or the same type of ignition yer engine has.
Hope I helped ya. JR
