What is does not say or show is if the coax coils can be placed so the boom goes through the center of the coils - allowing very good physical stability mounting location? Or must the Choke NOT be in the same plane as the RF element field?
It also does NOT state maximum pig-tail length between the driven element and choke coil.
What should be consider when installing this HF choke?
RadioWorks.com has a Yagi-balun?
How about using an UglyBalun?
Coax chokes (or ugly baluns) have inductance/capacitance values based on their cores which are invariably: 1. air or 2. a length of plastic pipe, cylinder or tube with suitable dielectric properties (this means than not just any piece of plastic will work).
A choke with a piece of metal tube going through its center is not going to have the same inductance/capacitance values as a choke with an air core or wound on a suitable dielectric form. Yes it would be mechanically nice to wind the coil around the boom, but the coil must be accurately designed to function appropriately in this form.
The length of connecting cable ("pigtail") is probably not critical until it becomes a significant portion of a wavelength (say .125).
You should consider what the purpose of the choke is before you decide whether you need one and whether to build one. The two references cited above will give you all the information you need to make these decisions. They are superb references.
Form follows function, or should IMHO. Decide what you want something to do and then decide how to build and install it.