It doesn't sound as if you don't need to spend the money on ball bearing swivels, they're mainly to prevent line twist when trolling. You could take a look at these Mcmahon snaps, very strong and they can't spring open;Cheers, i just don't want to use anything that could spring open with a good fish on. The Berkley black snap swizels seem ok, so do the Sampo crane snap swivels i will probably go with them then.
paired up with a 1/0 or 2/0 heavy duty Crane swivel;
They'll land any conger that swims......