We've seen a lot of opinions here over your problem, and I think you are probably taking the best approach in my opinion. Our guns are meant for fun and if they hurt us or if we have to go to unusual lengths to be able to shoot them....why bother? Your 40/70, or even a 40/65 would be a joy to shoot in that heavy rifle and you wouldn't have to carry pads, sleds, shot and all that other stuff to the range with you and grit your teeth when you pull the trigger.
I would suggest making sure of all arrangements with Shiloh beforehand. If you even ship it to them in a gun case, you will have it returned to you with a bill for it's shipping. Regardless of the case you send it in, they will sell you one of theirs for the return shipment. Shipping can add a lot of expense with them and you can figure on about 200 bucks in that dept. before you are done.