By weight, and approximation is generally good enough. Both pure lead and linotype are getting expensive and hard to find. You should be able to sell or swap the lead to a muzzleloader shooter. Two for one WW for Lead is not unreasonable and you may be able to do better.
My general purpose allow for many years has been 5:1 WW/lino. WW only runs me about a dime a pound. To get roughly the same hardness from lead, you would have to mix lead and lino roughly 50/50. That's a good alloy, but a very expensive one.