An alternative to limber holes?

I'm doing a major refit my 44 foot steel ketch, designed and built for the previous owner by the late Herman Boro in Western Australia. His designs weren't all that pretty, but the yachts were tough and very roomy. For some reason his designs only called for limber holes on both sides of the keelston rather than at the intersection of each stringer and frame. Although the boat is essentially dry, salt water did find its way inside sometime in the past. There are heavy oily water stains at every frame/stringer intersection and in some areas the paint has broken down and rust is starting to appear. I was thinking of cutting limber holes with a gas axe but I also considered bogging each frame/stringer intersection so that any water would run over the stingers to the keelston and eventually the bilge. At first I thought this may be a bit radical until a collegue told me that his boat has been done in such a way with concrete. He's in the process of removing the concrete because he fears that rust has started to accumulate under it. My keel is filled with concrete and steel punchings and it has held up very well for years. Unfortunately a large section of the keel needs to be replaced because of electrolosis, but when we cut inspection holes through the plate we found the internal paintwork to be in perfect condition. It looks as though the builder may have painted the inner keel, then coated everything with epoxy proir pouring the concrete. This may be the reason why the paint has remained in such good condition over the past 20 years. With the above in mind, I would not be opposed to fibreglassing the intersections before pouring in bog or concrete. Considering the volume involved, concrete would be a much cheaper exercise than using eposy and micro balloons.

As this is all completely new to me, I wonder if any members have attacked the limber hole issue in this way. Cutting the holes with a gas axe won't be easy, plus the strength of the boat will surely be compromised. Although I'm prepared to discuss the pros and cons of using bog, I'm really seeking advice from someone who has used bog or concrete as an alternative to limber holes, or knows of someone who has. As the stringers are only 1" high, not a great deal of bog is required. Therefore any additional weight added by concrete would not be an issue.