I replaced the keelbolts on my Pearson 26 this past spring. I torqued the bolts to something near 80 ft-lbf. Dan Pfeiffer's P26 web page has all the details on the bolt size (3/8" - I think??) and torque for a P26.
Overtorqueing (is that a verb??) can damage the bits between the nut and bolt (i.e. fiberglass and any filler material), and serves no purpose other than to reduce the "additional" load capacity (i.e. load beyond the load created by torquing the bolt - like holding the keel in place).