As much as I hate commenting on Goku threads, I feel obligated to out of love of Michael Moorecocks eternal champion, Elric.
Stormbringer does indeed help Elric over come his physical limitations, and as powerful as it is, I see no reason it couldn't cut and drink Goku's soul. That said the Goku can sling energy the likes of which would blow poor Elic appart before he got close enough to do so.
Let Elric have some prep time to summon some demon gods, and work up other such equalizers, and I think you've a much closer fight. Elric is a very powerful sorcerer in his own right, even without Stormbringer, but generally his magic is of a very indirect variety. Very little slinging raw energy, but very capable of doing some very very nasty stuff. I'm not certain if it'd be enough to for Elric to over come the raw power of Goku.
And now I've completely over-thought this topic more than I ever should have :P