lLooking to buy some cast boolits, Which ones?

I am planning on buy some cast boolits from Cabelas, Midway, ect. 45-70 400 grainers, and run them about 1400-1500 MV, I am looking for suggestions on whos and hardness to buy.
TIA,
Bob

For the velocities you'd be launching them at, harder bullets aren't going to give you any advantage, and if the least bit undersized, they will lead foul a lot more. Generally, unless you are shopping at The Bull Shop, commercially cast rifle offerings are not going to give you the fit to the bore that you need. Most are sized to the same as jacketed bullets, .002-.003 too small and cast of an alloy much harder than you need. Softer bullets even if slightly undersized will obturate better and give you better accuracy, but you are still better off slugging your bore and sizing correctly for it. Bullshop will use the alloy and sizer you specify to get the right match first time. If you are going to try commercial bullets, stick to the milder loads, watch for the groups to open up abruptly if you start leading up, and get a Lewis Tool to fit your barrel from Brownell's to get the lead out afterward. Just becaused bullets are advertized as a certain size, that does not mean that's the size they will be when you get them home, unless they are a custom job.

Remember that millions of bison were killed with soft lead plain based bullets fired mostly from .45-70's.......

the advice above is good and true, if you decide to go ahead and buy them anyways you will be loking for them sized 459 or 460.
you will want to see what kind of lube is available also, the hard parafin type lubes that most commercial casters use is okay in some situations but a mix of hard boolits and hard lube is meant for higher pressures and velocities.
the problem lies in that they aren't right for many rifles to begin with, and then not pushed hard enough.
cast boolits is truly a case of trusting the maker to have some knowledge of his product. [not his sales pitch]
but you have to also educate yourself.
or the old saying of "if you want something done right you gotta do it yourself"