I just went into the maintenance guide for the 1988 4.3 liter omc and just fir you to double check, here are some numbers.
The sparkplug : AC (delco) MR43T with a gap of 0.035 inch
Breaker Points: Dwell (degrees)39+/-2 Gap 0.019
Fuel : RON 93
Timing : 6BTCD
The reason why I wrote this down, is...