Proper BHN for Paper Patch 45-70?

[M71]

I received 50 PP bullets from a friend today. He's agreed to sell me his Tom Ballard adjustable mould they were cast with after I test them. I'll buy the mould anyway because I'll likely shoot them all up before I refine the particulars. I made up a dummy round to accurately measure the COAL. For the bullet to gently touch the lands and close the breech on my Roller the cartridge measured 3.2455. The 476.5 gr. bullet seated only .088 deep. When I receive the mould I think I'll need to adjust it to near maximum length to hand seat the bullet just a bit deeper. With minimal neck tension using fire formed cases the rounds are a bit awkward, I may need to seat them just before chambering.
I went to the scrap yard today and climbed into the "clean" scrap lead box and scrounged up 11 ingots, total weight of 53 lbs. I selected these particular pieces because they could easily be scratched with my thumb nail. They charged me $1.40 a pound. Ouch!
My question to the knowledgeable members is: How soft should my cast bullets be for Paper Patch accuracy loads? Perhaps 40-1, 30-1, or pure lead? My neighbor has 3 or 4 Hundred Pounds of alloyed lead he'd give me but he put so much antimony in it that it's way hard.

[Lead pot]

It depends on the naked diameter and the ogive length above the shank.

[M71]

The bullet is a tapered design. .460 at the base (patched), .443 where the ogive stops (unwrapped). The ogive measures .534.

[Don McDowell]

20-1 would be my choice. Tapered bullet like that doesn't necessarily need to engage the lands. Try different seating depths, and watch your fouling control.

[Lead pot]

That sounds like the same mould Tom cut for me. I use 1/16 Tin/Lead or 50/50 wheel weights/ pure lead an the nose will stand with very little setback.