Hey Beater;
Throw a tape measure along side the head. If it's a little under 2ft it's probably a 230. If its a little over 2ft it's probably 265 or possibly a 251. If it's way over 2ft it's the "big six" (these also have 6 intake ports instead of 3) and it's a real rare deal that may be as big as 413! In any case I think it's worth saving.

Leif