38 spl lift kit ball bearing size

[82boy]

I would also like to know how much of the case to leave behind the rim.

Cut the case down as far as you can go. The case head has a thick spot behind it, you should cut down to that level. The amount behind the rim is unimportant.

Finally, is there any value in using a 357 magnum case on my magnum rifles instead of the 38spl I will use on the 473 and 378 bolts? :) j/k

Nope, none at all.

"38 spl lift kit ball bearing size."

One that fits down in the hole. You just want a small amount of the bearing surface sitting above the case.