Slim, do yourself a favour.
Go with 1/2" barbs,fittings and tubing.
You choose a pump that has 1/2" in and outlet, don't spoil that flow with 3/8" restrictions !!
And the SB don't need watercooling, its tested and confirmed, watercooling the southbridge brings nothing more than good aircooling.
Pick up that cheap Evercool SB cooler, that's more than enough.