I've seen all but one of them...THE HEADLESS GHOST. I own it, but I haven't been able to bring myself to watch it yet. I guess you could call me a Herman Cohen fan. I'm even the guy behind the
Hermancohen.com website.
Far and away the
best Herman Cohen film is A STUDY IN TERROR, which is a terrific Sherlock Holmes film
and a terrific Jack the Ripper movie. Good stuff.
All of them are fun. The only one that probably shouldn't be on the list is DJANGO THE BASTARD (1969), which he really had very little to do with other than as a distributor. Likewise with his Italian giallo WATCH ME WHEN I KILL (1977).
A few notables that you are missing are:
CRAZE (1973) with Jack Palance!
CROOKS AND CORONETS (1969) with Telly Savalas!
DANCE WITH ME HENRY! (1956) with Abbott and Costello (their last film together)
KID MONK BARONI (1952) with Leonard Nimoy!
There are a few more, but not really worth mentioning or impossible to find.