For it to work on a omc you have to machine out aprrox 1" of splines. The omc has short splines and mercury has the long splines. The omc will fit right on a merc but has to use a short lock nut (have to cut one) and when putting a mercury modified prop on a OMC you have to run spacers under the nut. I have a 26 big ear chopper I modified for OMC. Works great. I know that omc has a 1 3/16 and 1 1/4 prop shafts but that is on the bearing surface only. Even the venom with a lightning case still has a "normal" size prop shaft. If OMC has a "fat" shaft I am unaware of it. To verify ...measure the spline diameter. Should measure approx 1"
If you have a over the hub prop that will not bite, it needs more cup or roll (cleaver style). One of my 26 choper would take a 1/4 mile to get out of the hole(seemed like it) took to perfomance and Billy put a little more cup in it, engine would rev to 4800 then bite and jerk a crick in you neck launching. The "OMC" chopper needs cup as everything I have ran it on blows out pretty bad. Props can be made to BITE hard or soft. Can't beat a good prop guy. Take 10 identical 300+ mercury engine all on allisons and whoever has a prop guy who can get it hook right will win!
