HELP, 64 Valiant motor mounts

I have a 64 Valiant. Its a slant 6, and I want to put in 340 in it. A friend got some early A body metal motor mounts off this site. I bought the rubber part of the motor mounts from Summit racing, and they won't fit the metal brackets my friend got from someone on this site. WHERE CAN I GET THE CORRECT mounts????
H E L P