Dear Boxkite!
Nothing special news for you according to P-10B.
Today I had call to Mr. Fortinov (deputy General Designer TANTK), who is the oldest designer in Beriev DB since 1949 (you may read his memoires "Simple Constructor" in www.avicopress.ru).
He told, that P-10B was only paper project by Anatoly Grigorievich Bogatyrev. It was done only 2-3 pix even without avantproject description. Engines were NK-8.
He also mentioned that there was an article by G. M. Beriev and A. G. Bogatyrev in soviet magazine "Life and science" No3-1963 where was additional pic and short story of this aircraft.
I try to find this ussue.
Sorry, but it's all what I can tell you for now.
Best regards