Just a few notes--If the 357 Barrel is a new one it will have more freebore than the older models. If it does you should be able to load the 180 XTP out on the second crip increasing the case volume and almost matching the velocity of the 158 with the 180 load--
second you may also have enough free bore to shoot the Hornady 180 SSPB--this bullet should fly a little better than the flat nose bullets.

Last do not overlook a big 180 WFNGC LBT style bullet

Powder choices would be 296 /110 and 2400