Welcome to the forum, it looks like the first Bill Shaw designed P39 was in production from 70-77 so there should be plenty of other owners like yourself looking for more information. Our PearsonYachts.org (http://PearsonYachts.org) web project is for owners like you and I will add the P39 to the forum.
Here are the specs of the original P39 from Pearson Sailing of Chesapeake site:
Designer Shaw Main Area 318/341 Hull Speed 7.34
First Year 1970 For Tri 364/376 SA/D 16.5/18.8
Last Year 1977 I 46.5 D/L 281
LOA 39.3 J 15.7/16.2 BR 43%
LWL 30.0 P 41.0 L/B 3.37
Beam 11.7 E 15.5/14.5 LWL /B 2.57
Disp 17,000 PY 20.0 OR 24%
Draft 4.6/8.9 EY 6.0 CSF 1.82
Sail Area 682/777 Eng D/A4 MCR 30.2
Ballast 7,300 Fuel 30 M/F .87/.91
Water 40 PHRF 132
Mast Height 50.3
(http://pearson323.com//images/p39.jpg)