Handicaps
A classic or vintage Finn is never going to be competitive with a current era Finn. However a classic Finn well sorted is quite capable of being sailed into the top half of a modern handicap fleet on the current PY number of 1070. My guess for a more accurate PY for a classic Finn would be about 1075 (i.e. fractionally faster than a new Laser).
For a Finn sailing with a wooden mast I don’t think there’s any reliable guide other than to plead with the Race Officer for leniency!
Further Reading
FINNatics published by the International Finn Association is now out of print but some chapters are available on the web site. In particular Technical Trends covers Finn development and includes good pictures of Elvestrom, Pearson and Mader Finns.
Finnlog is also now out of print. It was published in 1986 and largely updated in FINNatics
Elvestrom, Paul Elvestrom Speaks on Yacht Racing. Much good stuff on Finn sailing.
Both the British Finn Association and the IFA web sites have technical information.
The North American Finn website has an excellent guide to rigging, safety and sailing, most of which will be applicable to all Finns. Follow Photo Gallery, Jan Walker Regatta Photos, Finn Sailing