If you are using an array this old I assume it is for test/dev purposes? I would just direct connect one HBA and not worry about multipathing. ATF is really old, I have dim painful memories of using it on Windows 2000 Sever
ATF is now so old that you won't find the downloads here. Maybe someone still has it on 8" floppy (just kidding)
And the confusion on the FC numbering scheme is because the FC4X00 series came out AFTER the FC5X00 series arrays. I had a pair of FC4700-2 arrays on the floor starting in late 2000. At that time the FC5X00 series were already End of Life.