Getting into the counterweight part of the crane was my first issue.
There are spot welds around the top of the "lid". I drilled out the welds and the lid can be removed for really good access. This makes a great conversion in my opinion because of all the space. Be careful removing the lid and you will be able to use it as a removable lid to change batteries. I run two separate lipo batteries as well as lead counterweight and there is plenty of room for all of it.
I made all the rope drums for mine on the little unimat lathe. it works good on hoist and drag/crowd drums to make the diameter as large as possible and still let you "stack" the servos together. I made the boom drum pretty small diameter thinking I didn't want it to move fast. You could use that approach on the hoist if you were planning to do lots of heavy lifting but I don't think it matters much. I think this part of the conversion is more about making the servo mounts work well and easy to install, then make the drums.
Here is a pic of the pulleys I made for the boom required for dragline configuration. I really want to make a fairleed but haven't done it yet. You could probably just run the drag rope out thru a small hole in the front of the cab without the two pulleys. They way I have these keeps the drag rope from riding on the cab.
The house is simply sitting on top of the plastic gear. I don't even have a retaining nut to hold it down. Here is a picture of the truck chassis and the slightly different version on my custom crawler base.
When you detach the house from the truck, carefully grind off the top of the stud to leave the stud attached to the truck, and as long as possible.
On the truck, I did drill and tap the stud and add a cap washer and screw to hold it together. This way if someone picks up the house it won't separate from the truck.
Here is the crawler version, I enlarged the hole and made a large post/stud to mount to the crawler base. This has a small center hole to hold the slip ring needed for power transfer to the tracks. My plan was to mod the truck to match so I could move the crane back to the truck if I wanted.
Feels like I have hijacked your build thread, sorry
Jim