Stephen,
Gary has pointed out in previous posts that the Amidon's thickness, .5" OD, prevents it from being used where the stock ferrite lies. Major plastic trimming to allow a fit looks risky in that it appears trimming would have to be done on a circuit board as well. The risk would be cutting board traces that interconnect components.
I have ordered some flat lipoly batteries that will fit in a vacant spot in the radio. I plan on checking the charging circuit in the rx to see if that will work with these batteries. I don't forsee a problem. I will alligator clip them to the correct spots in the existing battery box for testing the charging circuit.
The plan is to then use a 4" Amidon .5 OD rod where the two batteries lie inline. With a minimum amount of surgery, a 5" Amidon work could fit inside the cabinetry. No circuit boards are at risk. I have a 6" rod that I can trim.
It will probably be next week before I do the work.
Once again, I try to "fix" a radio that isn't broken. ;)
73 Gil