Might as well try it. I had a 350 that I ran perfectly at 400, so I don't see why a 380 should have much trouble. You're correct on how to do it, just bump the FSB to 100 MHz. My guess would be you could also get away with 112x3.5, which would give you 392. The 392 would probably out-perform a 400, since the L2 cache speed will be 12% faster. If you have RAM that will do 112, go for it.
Viper GTS