You can load the Lott to 2300 easily with no pressure issues .. If ya have to have a few extra fps , then make it an Ackley , then you could shoot the Ackley , Lott or Win Mag as well in one rifle ..
Get the Lott and be done with it .. If you're shooting a bolt gun at DG , then magazine capacity is more important than a few feet in velocity ..
I can assure you that anything properly hit will not know the diff between the Lott and Rigby ..
The belt isnt totally useless in the larger calibers .. Ammo availabilty in Africa is a joke regardless of caliber .. And very expensive to boot ..