My personal recommendations for a standard SAA would be a .357 Magnum of you do not reload, a .45 Colt if you do reload. .357 Magnum also encompasses .38 Spl; and can be loaded mild to wild in factory bought ammunition. Ain't much a properly placed 158grn or 180grn HCGC .357 Mag won't drop down here in the Deep South, my friend.
Regarding requirements OP have;
.357Mag vs .45LC in single action revolver, I am not saying that he shouldn't consider Italian clones, but IMO Ruger makes just better SA revolvers. They might not have case coloring and other nice looking details, but Ruger revolvers are STRONG, STURDY, and if something goes wrong, they will fix it, or replace complete revolver. Can't ask for better customer support!
As for caliber, I don't have any doubt that
"Ain't much a properly placed 158grn or 180grn HCGC .357 Mag won't drop down here in the Deep South". Heck, one native in Canadian North was hunting polar bears with 22 Hornet. Bear almost wouldn't react when hit in abdomen, and hunter will just wait and later track it down. Because of internal bleeding, within several hours bear will be dead.
My point is that in most cases 45 Colt will do better job than 357 magnum. If you check loads here
https://www.hodgdonreloading.com/reloading-data-center for 45 Colt (NOT 45 Colt for Ruger, Freedom Arms and TC only), there is a load that will lunch 255-LSWC at 1011 fps and 14 000 PSI. That is basically a black powder pressure level. I have no experience with Italian clones, but I bet any of them will take such load without problem.
And that is not whole story. As others pointed, firing top load 357 Magnum without ear protection, just one shot will make ears ringing for days. Several shots in a row will most likely make permanent hearing damage. However, 45 Colt at 14 000 psi is no popcorn pop, but not nearly as bad as 357 Magnum at 35 000 PSI, some loads at Hodgdon website are listed as high as 40 000 PSI.
Regarding weights, as far as I know, no 357 Magnum revolver is manufactured on smaller frame that those used for 45 Colt. So, in that respect. 357 Magnum revolver on the same frame must be heavier than 45 Colt.
Just my .2 cents...