Alby,
give SIMPLEX a call, they may be able to help you out - worth a try.
If you have a few fired cases they should be able to make it off those.
Peter Davern did that for me for my 9.3x64, that was in the mid 80's
They do make 577-450MH dies & its not on their list, very good quality.
https://simplexreloading.com.au/contact/