I know this is a league forum and all, but I've had a bit of time recently and I looked at how you would convert "Stacey Jones Rugby League" into a union game.
From what I've come up with, I think that converting it could happen, and you wouldn't have to start from scratch. There are some obvious things such as lineouts, rucks, scrums (real ones), etc that need to be changed but there's also a solid base to build off including kicking, button configuration, graphics, running passing, most tackling etc. I've got a long list some where, I might put it up on
www.therugbyforum.com (should be back up) or if you're interested Mario I could PM it. I realise you must be busy now with the PSP thing, but I hope you seriously consider it for a realise in 2005 when I believe a lot of rugby game licenses are freed up (hint). If you could get franchise in then you'd have one up over WCR (which I think will be good, but two quality union games are always wanted) and about 500 points up over Rugby 2004.