Which sabots? The PR Orange or the MMP Blue? Both are made by MMP but the PR sabot is longer.
In the Blue MMP sabot, the best groups i got in a Elite 45 1-30 twist were with the Hornady 147gr 9mm HP with the mini boattail. About 60gr of BH209 gave "ok" plinking accuracy.
Any 357 longer than a 158gr is probably going to be better off in the PR Orange sabot. You might also try sizing the .358 bullets down to .355 in the Orange sabot. They can get really tight and .355/9mm fits much better.
A fast twist is a must with the .358 200gr FTX. All attempts to shoot them in a slow 1-30 twist failed. Bullets either keyholed or the sabots drilled with heavy loads of BH209. I also tried them in a 1-28 twist with no luck.