I've done gabion baskets, there no fun!! They are very labor intensive, make sure you rent a air gun to hog tie ring the basket together, that will help speed up quite a bit. We always place the stone into the basket with an excavator or I've used a backhoe, then hand place to fill in the voids and like someone mention you'll have to cross tie them in 1/3rd intervals or halfs. Small crow bar will become your labors favorite tool to pook rocks into place and help close the baskets together. I'm surprised they call out #57s that have to be compacted, we always backfill with gabion rock so you don't have to compact between the wall and dirt slope, cut the slope as tight as you can so it don't eat up to much backfill. I'm sure a Cat 304 will work but I've never used anything small than a 308 or Kom PC88. You don't want to much machine as you want to beable to place the bucket down into the basket. We always dipped the rock out a rock box on a trailer or out of the back of Tri-axle. This will help save on rock and not get mud into the baskets and leave alot cleanier jobsite.