As to the Foxtrot Big Bow, there is a picture of one B-51, number on the sail 995, with a large sonar installation on the bow, no date given for the photo.
This sub was transferred to India during April, 1968.
From: Warships of the USSR and Russia, 1945-1995
Author: A.S.Pavlov.
Translator: Gregory Tokar.
Editor (English Language Edition): Norman Friedman.
Naval Institute Press, 1997
I can find no information on the Yankee class sub.