The prudent answer would be that the head stamps should match the firearm. If they don't, some official may refuse to let your ammo in leaving you to buy it somewhere at your destination and in your case, you probably won't find any at your destination.
When I went to South Africa, no one checked head stamps and the experiences of others has been the same. I think you would have at least a 90% chance of getting incorrectly marked brass into the country; only you can decide if those odds are good enough for you. It's also possible, though I wouldn't bet on it, that some official would listen to reason if the headstamp question came up. You would also probably have a better chance of getting it in with a service like Air 2000.
Here is a source for 358 STA brass from Quality Cartridge:
http://www.qual-cart.com/headstamp.htm