well the only issue i see is with cast lead we shoot oversized boolits so you would want something in the .359 to .360 range. i would think that the .358 wouldnt give good barrel fit and possibly cause leading.
The thing that I was worried about is if seated to crimp groove will the bolt still close without problem?
Man those 190 gr bullets sound good. I also found this here http://magnusbullets.com/store/page5.html the 200 gr one, but looks like you can only get them in 357. I emailed them last night to see if they can make them in 358 or 359.
The best bullet I have found so far for my rifle is seaco #351 sized to .358 http://www.westernbullet.com/sa3gr2.html. Trimmed brass,6gr of unique with a little wad of toilet paper stuffed in the case to hold the powder down, Win primer and seated to crimp groove those bullets shot 2 inch 3 shot spread at 200 yards!!!! (I'm not making it up, got target to prove it ). But, the bullets are out of stock now and people who run the western bullet store won’t answer the phone or the email. I think that’s bad way to run a business.
Any bullet you can get to feed and chamber will work if the diameter and powder charge is correct. Seating to the factory crimp groove matters not to the rifle. You have already proven .358 does fine. Your charge of Unique may need adjustment but it should do good as long as you keep muzzle speed below 1,000 fps so they don't strip off the rifling.
I've never heard of Western Bullets so they must be small. Be patient, small businessmen have health and family problems as much as anyone else and they need an occasional vacation too.