Your safest bet would prob be Owner ST66 in 4/0 or 5/0. A strong hook with a lot of GT fishing history. In GT terms, quite a 'light' gauge hook, so you don't run the risk of swamping your Halcos - making them a sub stickbait! I run them on a lot of my lures, esp. gammas.
You will also then need to upgrade your spilt rings to accommodate the new choice of hooks.
In regards to singles, Owner SJ45, 47, 51, Fisherman Shiaden, Varivas Seriola, Shout Kadako, Shogun Extreme assassins and Vipers....all these hooks seen to make their own guidelines for hook sizes - a 5/0SJ45 is not comparable in size to a 5/0 Fisherman Shiaden. The Owners and Shiadens will also work well with a Baker belly rig. Also suggest using 2 split rings to make your hooks run the right way. If you use Shogun Vipers, these are an inline single to only one split ring is required.
Hope this helps you out,
Cheers
Kurt