I acquired a 1979 J-30 with the same problems about 2 years ago. I had put in a offer on the boat and backed off when the survey came in due to the moisture issue (wet on the starboard side below the waterline from the exhaust pipe to about 6 ft. back of the bow).
The owner was very distraught over the condition, realizing that the cost to repair was probably close to the value of the boat. We ended up working a deal wherein he donated the boat to a local charity and got atax write off that was bout 20% higher than I was originally goping topay for the boat. I executed a 24 month lease purchase agreement wit the charity at a greatly reduced price, that essentially was interest free financing of the as is vakue of the boat. I spent a year trying to passivel;y dry out the hull by drilling holes from the inside and applying heat and a de-humidifer -but with very limited sucess. I ended up paying to have the the transom rebuilt around the exhaust tube, re-core the starboard stern quarter (about 15 SF), had the keel joint completely rebuilt, the keel faired, and all through-hulls below the waterline re-beded - all told about $10M worth of work. I know that as time goes on I may need to do some additional re-coring on the starboard side but I'll address those issues later. In the end I will have spent about $15M on the boat but it is now in the water and sailing beautifully.
I was lucky in that even though the boat was wet it was still reasonably stiff - no inward flexing visible at the lifeline staunchens.
Also, when I drilled the holes into the hull when I was trying to dry out the core myself, most of the core though reading wet on my moisture meter was in pretty good shape, light in color and although damp to the touch, not saturated other than in the area I had recored.
The bottom line is hat the J-30 is a great boat, and there is a "right price" if the seller understands what he has and is willing to negotiate in good faith.
