I have an S2 27 as well, but it is a "Model B," built in 1987, hull #80. I have not done this job, but I am pretty sure that all my keel bolts are identical diameter. In 2008 when the boat was surveyed, the surveyor's recommendation was to replace the rusted ferric washers on the keelbolts, rebed them with 3M 4200, then re-torque the nuts to 65 ft-lbs. I haven't done that yet...
Check out and join the "S2 27 Class Association" Yahoo Group, if you don't know about it.
http://groups.yahoo.com/group/s227classassociation/
There are numerous pictures of the two different bilge configurations in the "Photo" section. Don't know how many total owners are members, but we would like to increase the number. Welcome.
The nuts on the keel studs are rusted and need to be replaced, has anyone done this on a 27' there are two 3/4" and five 5/8" studs. If the studs are made from 18-8 or 316 SS which would only have a torque of 43-45 ft-lb for the 5/8" and 92-96 for the 3/4". Does anyone know what the torque is to be on these or does someone know what material the threaded studs are made from? The studs and washer are in good shape.