OK, I got around to testing some of the 370 grn linotype bullets ( RCBS 43-370-FN).
At 1700 fps they are close to the old 450 BP cartridge. That was a 365 grn hardened solid lead at 1700 fps. That load was used on all African and Indian game, and Pondoro Taylor was very fond of it as well as Selous and a host of others.
In my 11.2x60 that load went 18", cross grain of dry Rock Maple. I kept splitting those big blocks of maple expecting to find them with each chunk I took off. It made me a believer that the old 450 BP really could be used on the big stuff.