Sorry that would help. I'm installing a ls but I even tried a small block with no pan. Get one bolt in and the other side is a 1 1/2 in off. Talked to heidts and the told me what mounts to use and that did't work.
I don't have super ride or an ls. When I did M2 I didn't install the shims that go to the firewall first, or the heidts mounts and nothing fit right. I fit all the shims and the heidts mounts and everything lined up. maybe your problem is different. just trying to help