So I'm not a fan of the standard (or Treason) O-Yoroi sculpt. Too gangly and awkward. The Guijia on the other hand is a nice shiny new style model, and aside from having a weird hooked sword, has the correct weapon options. Now, I'm no master converter or anything, but I figured i'd have a go at reshaping the sword into a more suitable (oversized) katana, and since I picked up a second JSA Army Box, I had an extra Daiyokai helm that I thought would look pretty decent on there. The sword needs a little more work but otherwise I'm pretty happy with the results!
Noice. I converted my own Guijia to an O-yoroi last year (I'm just not a fan of skinny mecha piloted by neurotic schoolgirls). I just reshaped the hook sword into a katana rather than made a new one (I did, however, carve a new tsuba from plasticard). I also removed the HMG from the back mount (which meant carving a new back "hoop" since the gun is attached to that part) and made the TAG hold it in its other hand (the grip fit into the hand, some slight bending of the fingers allowed it to "hold" it.
Wasn't a major "conversion". Changed the ccw to look more katana-like from the shuang gou and took the hmg off the back mount to make it hand-held. It's mostly a JSA paint-job (the left shoulder pauldron has a rising sun on it) since JSA can't HAVE a He does have a sashimono that I have to magnetise and there are plans to give him a kabuto helmeted head with mask to replace the stock head when I get around to playing JSA again (6 armies, I have them on rotation so that they all get played, it just means it can be up to 2 1/2 years between their "turns".) and that next time for them is late next year.