moving teams is not as simple as it sounds. As I recall we looked into what happened when teams were promoted and relegated and there's a lot of stuff that has to change. Since (almost) none of the players in the old Amiga version are still there (David James maybe?), it's the players that is the real work anyway to be honest.
Not sure if I will be able access the source but I will try. You guys should try and contact Paul and see if he still has it. Is Amos Professional available as a set of adfs or something? I don't mind doing a bit of work on this but I think I'd have to use the PC + emulator really. If I can get AMOS pro working in WinUAE then I could take a little look.
What would be interesting is if we were able to get a conversion process going between new FM data and the old one. That would potentially allow the system to convert some of the data for you.