you have to test on your own
each 380 i have  have different results and they not all on the same setting to have the best speed

but i see people overclock the memory but it has no effect because memory bus is not load at 100% (70 only)

and try with --cl-local-work 64 128 256   --cl-global-work from 8192 and up

i have some running at 16384,20480,26624 with --cl-local-work 64  for r9 380, asus, msi get some higher speed than sapphire & xfx
but there also difference with same model

gpu overclock has no effect (i try up to 1060) so i run them all at 1000  and memory 1400&1375 (i try run them all at 1400 but the asus did not like so i keep a stock 1375 anyways no difference in speed)

the asus stock speed is 970 the slowest  but it s the best card (+- 1.7mh more than xfx & sapphire what run stock at 1000