I would suggest the collapsible metal dog crate type for macaws instead of the plastic type, for a Greenwing you might be able to get away with the 36" size, but you may have to go to the 42", I like the fact when their not in use they fold down to just a few inches thick, also have a removable plastic tray on the bottom for easy clean up, they can be fairly expensive so you might try looking on craigslist or garage or yard sales first, I picked up a 36" crate at a yard sale like new for $25, heres a link so you can get an idea what I'm describing, not suggesting you buy from this site
the one i have now is the nylabone collapseable one but the vet had a hard time getting him out, thats why he suggested the kind where the top part comes off
I'm sorry I forgot that you sometimes have a difficult time with Remington, I usually suggest those types of crates because of the destructive nature of macaws, because of their long tails the size of the crate will still be valid, 36"-42"