Currently on eBay there are mid 1990 55 hp lower units and they are both 2 bar units. My 1994 70CES lower unit is a 2 bar only the first bar is cut out a bit. These lower units were used with the 6F0 49 cubic inch motors as well so exhaust flow thru the hub should be OK with the triple. The 6F0 model has the shell style muffler like a 70 hp. Maybe the lower end of that muffler can be cut and welded on to a 6H3 muffler and then the exhaust will flow directly into the lower unit.