Depends on what you want to spend. Lower end scopes like Millet TRS-1 would work. I would recommend a bushnell elite 4200 or a Vortex Viper PST. Probably want variable magnification like 4-16x or 16-24x. I am running a Vortex Viper PST 4-16x50.
I have a slightly used Magpul PRS stock kit for sale. It is the complete kit.
Only trade I would consider is the UBR stock kit. That is it.
$200 OBO
http://i18.photobucket.com/albums/b128/1fast5gp/Magpul_PRS_Stock_KIT_-_Black_zpsa7b37b09.jpg