I believe the 216 flywheel had 139 teeth and the 261 more than likely had the 168 we are all see as normal. I believe someone on e-bay listed a 12 volt little high torque starter that bolts on the early bellhousings with the 2 horizonal bolts but I haven't seen them lately
I had 2 adapters made 20 years ago to put the little starters on my race cars with the 139 tooth wheel. Funny thing is the original Nissan starters (where all of the little V8 starters came from) originally have the proper gear (number of teeth and pitch) for the 139 tooth old Chevy and GMC flywheels. Any good starter shop can change this out for you or you can do it yourself if you find the conversion and it has the 168 tooth ring. Personally I have used both the 168 and the 139 in a stock bellhousing and prefer the 139 because it turned the engine over faster....Good Luck
