About the best you can do is find the average muzzle velocity of that ammo by running a sample of about 10 rds. through a chronograph. The main problem you have is the ammo in question is Monarch which is a generic version of Barnaul,a Russian ammo mfg.
However in your case the 357 ammo in the Monarch box probably has a nny headstamp which means it was actually made by Prvi Partizan and sold under the Monarch name,this is very common Prvi also make alot of the Wolf Gold lines of ammo.
So basically your going to have to start form scratch using available primers,powder and bullets and work up a new load for your .357. Graf and Sons on occasion carries the 158 gr. SJHP used in the Monarch ammo but there currently out.