have a look on here or there is some good build log's if you search for "800d build logs"
I had the ATCS 840 and a PA120.3 and i can tell you that the fan spacing will mean that it is difficult to mount with out modding (not impossible just a pain). I got rid of the case in the end as the cable tidying is not as good as the corsair models for example. Other than that the case is well made and nice looking.
Double check which PA series you have, if it is the last revision before the TA then it means you have 15mm fan spacing which will allow it to fit in the ATCS. If you have an older revision of the PA then the spacing will be larger and you will not get it to fit with the provided ATCS mounts and fan mount holes.