Did it last year on my 80-H27
Last year I had her sandblasted. After thorough dry out, all blisters were filled, the hull and keel faired and 7 gallons of Interprotect 2000 applied. It wasn't necessary to replace the through hulls. They were all bronze and in great shape. I did replace gate valves with sea cocks. If I may recommend, since you're doing all this work, use Micron CSC bottom paint. I used green as a first coat and then 2 coats of shark white. It held up great! No need to repaint until the green base coat shows. Boat US has a sale on both: $44.95 a gal. for Interprotect 2000 and $119 a gal. for Micron csc. Good luck...it's worth it.