small block 73&up to bb conversion mounts needed

Those mounts require cutting the driver side saddle and drilling a new hole for the through-bolt. Why don't you go over the www.bigblockdart.com adn look at the tech pages for making your own DC k-member and buy some 74-78 passenger car factory big block mounts. You'll be money ahead if you can weld it (or have a friend who will).