We were discussing octane earlier. Note the (R + M)/2 you see on pumps in U.S. This average of the RON & MON ratings is also called the PON rating referenced earlier where I stated:
In your 1964 Owner Manual on page 36 it indicates to use Minimum of 100 octane RON, or 89 octane MON. If you do the math to get the PON # that comes out to 94.5. So..that means the 93 Octane Premium in the US (PON) and the 99 Premium in the UK (RON) are both just tad lower than the recommended minimum octane for our 10.5 to 1 compression engines. My 64 CDV runs fine on 93 Octane, however, adding octane booster seems to give it more power. Keep in mind that the 94.5 would be a minimum recommendation and not an average or maximum recommendation.