sorry i didn't get back to you guys,
One thing to note is I've gotten a few all original girls bikes, where the BB and crank have never been removed.
I had to build up a prewar for my wife and had a few sets of Schwinn cranks and front sprockets laying around.
Some of the sprockets would not fit the cranks. As the sprockets were specific to certain cranks. All Schwinn parts.
I'm in the process of moving but I'll get pics to prove this when I get a chance. I can measure the arms on the girls bikes tonight though.
Yes it is possible to have the shorter arms on a Schwinn crank for ladies, and the smaller sprocket, it makes it easier to pedal. Some older guys add these to their bike to make the boys bike easier to ride.
that is why no all the girls parts are directly compatible with boys bikes.
The same hold true on Boys and Girls Monarks. If you get a girls monark with a 52 tooth gfont sprocvket, it incorrect for that bike.
the whole is NOT to far fetched as you should know the is difference between boys and girls seats and pedals and bars.