Need advice on how to pick appropriate ferrite material for use in
baluns. In this case, a line isolator/choke to stop common mode current
on the feedline to a Carolina Windom.

Specifically, if EPCOS # B64290-L638-X35 cores would be a good choice for
such a project. What little information I have managed to find for this
part number does not help me much.

OD: .870"
ID: .539"
H : .25"
AL: 3200
ui: 5300

Looks like they would not be very snug on RG8, but could easily get a few
turns of RG58 through a stack of them.

--Teh