I just put a 505 "B" block in my Challenger and used the mity mounts from Dyna Tech. Not cheap but not as expensive as the Schumacher mounts. They're like a rubber mount but they kind of internally lock together so it won't pull apart like OEM rubber mounts.
I still plan to put a torque strap in just to be safe. I had a hot 440 get loose back in the day and I don't ever want to experience that again. It pulled the throttle cable out of the bracket and it went wide open. One heck of a smoke show!
www.mitymounts.com/howtheywork.htm