You can buy the dies at CH4D die company. I don't know about the reamer print.

http://www.ch4d.com/products/dies/caliber-list?filter-col=caliber&filter=&page=64

Yes, I use .404 Jeffery brass to form cases.

Mine is built on a CZ 550 Safari that was a .458 Win mag. The gunsmith set the barrel back and "cleaned up" the .458 chambering.
[Linked Image from i.imgur.com]


Found this....
https://www.24hourcampfire.com/ubbthreads/ubbthreads.php/topics/5137169/450-howell

Life Member SCI
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Member New Mexico Shooting Sports Association

Take your responsibilities seriously, never yourself-Ken Howell

Proper bullet placement + sufficient penetration = quick, clean kill. Finn Aagard

Ken