Good move, John.

Not sure about sizing partitions - don't see why not as the Noslers have a fairly thin web, but maybe it's too much.

H-mantles should be easy enough as the web only goes in a short distance.

I don't know anything about T-mags.

A phone call to Lee is usually required as custom dies aren't listed on the web site - thus no button to click for them.

A .335" and a .332" should work fine. There is generally a bit of spring-back in the bullet, so the bullet will end up at .332" to .333". Spring-back wold suggest loose jackets, but that does not seem to be happening - accuracy is super and penetration is even better than the original bullet provides.

The 2-die set would allow sizing down harder bullets, ie: bullets with harder cores, thicker jacket - easier for the partitions, that sort of thing.

The base plunger (pusher) comes with the dies, along with lee liquid Alox, which they say is easier for sizing jacketed bullets than Imperial die wax or other waxes or oils. I have several bottles of it, so I will have to try it myself.