I had 2 die sets for my 45-70 and 45-120. The first set was a standard RCBS 3 die set for jacketed bullets, the other set had the 3 die set as well as additional dies for placing gas checks, forming gas checks and a special seating die for cast lead bullets with different seater plugs. Depends what you’re doing with it and, what bullets you intend on using.
I use RCBS dies I got at a garage sale back in 1972 or 1973.I ordered a seater stem so I can seat hard cast lead bullets. I love my 45-70 and 420-465 gr hard cast bullets will kill anything on the planet.
I use mostly cast bullets in 45-70 .I have some Hornady 350 gr bullets(I think) they kick more than 405 gr,465 gr hard cast Cast Performance bullets. Easier on the barrel and kills beyond normal!Just got to slug the barrel to make sure of fit. Many years ago I shot a bear with my 44 mag hand gun with 310 hard cast bullets and it went right through the bear like butter.