Your first example pic has a single 'horizontal' Sheeve at the bucket, that floats in the mounts to keep the sheeve inline with rope pull
https://i.ytimg.com/vi/MDnxrDHvqoU/maxresdefault.jpg
Looking at this model,
What if ya drill pair of holes on Right and Left side walls at Top Aft corners of Bucket for a steel axle to run left-right. Chunk of brass tube that runs over the axle right-left just under the width of bucket to move freely, roll a sheet of flat brass around the tube, extend the sheet up far enough to house and guide the rope around the pulley. Little solder, poke a couple holes, print a pulley. Maybe even skeletonize the down/aft side to help it shed dirt from pulley?
(Basically making a bigger version of your Nylint cranes Boom elevation tip pulley, but where that wire bridal ties it to boom is your new axle in the bucket)
Or the bigger machines often ran a pair of taller 'vertical' sheeves, which could probably just be done with putting the pair of pulleys along side the dipper stick with a couple spacers inboard of the pulleys. I doubt you'll need that much mechanical advantage.
Similar to the set of outboard pulleys on my Michigan (boom angle)
This seemed kinda cool, talks about history and why dipper powered crowd works
https://www.inventionandtech.com/con...-build-america