The R200 Ready Rail has an installation depth range of: 27 1/4" to 29 3/4" The overall mounting depth of the entire assembly is 35 3/8"
The PE1950 Universal Rail has an installation depth range of: 26 5/16" to 29 9/16"  The overal mounting depth of this assembly is 36 1/2"
I don't know the exact dimensions of the PV NF500 but it's close to the same.

All the standard Dell Rail Kits are compatible with Square Hole Racks, so your good there.  Your issue is that you have a shallow and a deep rack, both of which are outside the installation depth range of the rail kits.  There are several options available to resolve this issue.  There is a complete assortment of brackets that will extend your shallow rack as well as reduce your deep rack to within the range of the Dell Rail Kits.  Another solution is to use a generic rail kit that has an installation depth range that will work with your rack.  Either of these solutions will work very well.  

If you have any questions give me a call.

Will Beene