I'm the owner of a 23ft John Allmand 1966 .The motor did have a crack in the cilinder.I maybe able to fix it.But Luck was on my side.I found a complete 1969 Buick/OMC from carb to pan for $500.00.It was winterized this real auto coolant.I put my new carb on,replaced a few old wire connections and fired that motor right up while chained to the cherry picker.We installed it a few days ago.Now to redo some dash wiring,check the lower unit,sand,more sand ,paint.... I don't think I should add any more.It is a never ending story any way.I will try and get some pictures soon Dan