The RZ has a lot of electrical components to it. I looked into doing one on my bike, but with the cost and all, it does get up there, I decided to go with an MX port instead.
On the RZ you also need intake flange adapters, the banshee has a spigot setup, where the springs hold the headers to the bike, where as on an RZ, a flange(like on a 4 stroke) holds the header to the bike. It's not a big deal, but you will have to make an adapter, or have someone else make you one.
Also, only certain pipes will work on an RZ, because the powervalves get in the way. You will need either PT mids or high revs, or older Rocket Pipes.
The elctrical is a bit tricky too, check out the parts microfiche for an 85 RZ350, the wiring harness has a TON of wires, most of which you won;t use. The powervalves also run on DC, so you will have to either rig up a battery or a rectifier, and you have to make a special place to mount up the servo on the bike.
Like I said, I don't know much about the other 2 setups, but from what I hear, the 404 does suck, and I know Daj is almost always on spot with his knowledge! If your just starting out, I'd say stick with a port job first, and you could always upgrade in the future. I still want to do a RZ engine, but I don;t ride enough to justify it, and an MX port kicks some serious ass and is alot cheaper.
There is also a ton of good info on here, and I would check that otu as well, the search is quite useful! There are also a few people on here that have done the RZ conversion.