From my experience balancing and the ratio of microballons are closely related. I've gotten a lot of help from the TU community and Matt's 1-1 ratio is the best place to start and the overall consensus for general buoyancy. One thing I can add to this is that this ratio will almost certainly need to be modified to fit the bait you're making. I find that there is distinct actions that happens when the ration and ballast / balance is not quite right (apples to lipless baits) , the roll and a dead action retrieve.
Roll / wobble: if you get a roll or wobble when you retrieve the bait I've found that this can usually be fixed by making the bait more buoyant
(adding more microballons) and adding more ballast. By doing this you are applying more force in the upward and downward direction forcing the
bait vertical. In my experience this help with roll in any sink rate you want. The only downside to this is that the more balloons you add the weaker
the bait gets and if changing the ratios doesn't fixe the roll problem then it's probably the shape of the bait.
I've always though of it like this, a perfectly tuned wood bait has the most amazing action. Most wood used for baits is fairly light and buoyant, try to replicate wood then fine tune you ration and weight to get the exact action you want out of it.
I hope this isn't too fare off topic.