About Suspiria: All the blu-rays look horrible thanks to oversaturation in some parts as well as very crushed whites and blacks in other parts. There is no way to bring back something that's not there.
The only version that seems to look very good is the Swedish Atlantic Film DVD. Check this comparison: http://caps-a-holic.com/vergleich.php?vergleichID=123
Unless a new version in HD is found, the only thing that could be done is to upscale that DVD.