I tried 44 dies and they hit the case way before the bullet is seated due to the taper of the larger case. so I think it is safe to rule out 44 dies except possably shortend way down and then only to crimp. I was able to make my rounds with just 444 marlin dies and some misc die parts that to be honest way over expanded the neck and would not reach far enough down to do the rest of the case. there are commercialy avaliable expadder dies that will work. all that needs to happen is get the case expanded sligtly over size 75% of the way down. resizing it in a 444 marlin die will get it back to were you want it.
A few thoughts - you may be able to get away with .44 mag dies, just run them in shorter. Maybe... depends on case diameter at the point where a .44 base would normally be. That, with the purchase of a .444 Marlin full-length sizing die, and you may not need to make any mods at all!