Here's what Tom Kolb and I did:
http://www.larp.com/legioxx/Qrepub.jpg
Though now I use my hispaniensis,
http://www.larp.com/legioxx/hispan1.jpg
http://www.larp.com/legioxx/Smihel1.jpg
http://www.larp.com/legioxx/rcRD28.jpg
Also an older photo, with the that old MRL Fronton style sword which we now know is too early (and no relation to the Roman hispaniensis or Mainz). Johnny Shumate's painting shows a Fronton, too.
Of course, you can use an earlier Italian style sword, IF you can figure out what it should look like, and how to make it!
The pectoral is the way to go. Tom went with a simple fairly plain one, just a scribed line border. Mine is based on one shown in Connolly, which I now expect is MUCH too early,
http://www.larp.com/legioxx/pectoral1.jpg
The way the shoulders and sides are done is more 3rd century, if I'm remembering correctly, but the dot pattern is practically Villanovan. There is some debate about shapes, with some saying the rectangular ones are all earlier, with round ones being better for this era. But then you see those nifty Samnite muscled ones! The triple-disc style is cool, too, and Deepeeka makes a decent one.
Mail is *not* indicative of a triarius. One's status as hastatus, princeps, or triarius depended on age and experience, whereas armor was dependent on wealth. It's entirely possible that the proportion of mailed men was higher among triarii, but you'd still see plenty with just a pectoral. Besides, once you've done an event in a pectoral, you'll never want to go back to a hamata again! THREE POUNDS, dude...
Belts? WHO KNOWS! I used belt parts from Numantia cuz I had to use SOMEthing... Heck, we don't even know what their shoes looked like.
My shield didn't really come out to the shape I wanted (too squarish), but I do like the all-wooden boss. Deepeeka's Republican scutum isn't bad, but the boss is HUGE.
That help? Vale,
Matthew