Thanks for the help and advice!
Here's how I plan to go forward for the rest of the kit:
The sling will be linen. I already have a pugio, but I need to modify or make a new scabbard, as it is a Titleberg scabbard, which is slightly innacurate (reply #5 of
this thread on RAT). The shield looks to be an oval shape, so I am making a clipeus shield (based on the
Legio XX Scutum page). I still need to get wool for a tunic and cloak, but depending on cost and my budget, I may omit the cloak for now. The belt could be another sling, a strip of linen (
Legio XX Tunic), or I could finally start on that belt I have all of the parts for and have been putting off making for over a year now.
If anyone notices anything historically inaccurate with how I plan to construct the kit, please let me know.
The thread on Roman Army Talk:
https://www.romanarmytalk.com/rat/showthread.php?tid=31724&pid=353458#pid353458