If your just wanting to attached a JW Ultra bell to a stock case, you can do it with brake lathe like above but we've done a ton of them with a Sawzall, it's not pretty but all your doing it cutting the stock bell out of the way so the ultra can mount to the pump bolts so you just cut it at a little bit of an angle. (the pump is mounted to a machined surface inside the tranny and the ultra bell mounts to the outside pump surface so don't need to be precise)

I know of 100s of them done that way, yea it's crude but it works just fine.

I run a JW Ultra case and Ultra bell now but ran stock cases for year without any trouble.