The rear reflectors are not cheap, here is a set on ebay.
http://www.ebay.com/itm/1965-1966-Nissa ... R5&vxp=mtr
http://www.ebay.com/itm/RARE-DATSUN-520 ... w6&vxp=mtr
Here are a set of front 520 turn signal/part light assemblies on ebay.
http://www.ebay.com/itm/Datsun-520-turn ... nj&vxp=mtr
I have a used set of early type rear 520 assemblies, but not sure what I want for them at this time, if you want I can take photos of them.
I also have used cab mounts for the 520/521, I would have to see a photo of your rear bump stop mounts on your frame, I have a set, but not sure if they are 520 or 521, I cannot recall if the 520 side mount is on the inside or outside of the frame, maybe they are interchangeable?
The upper front bushings on ebay also, you will need 2 sets.
http://www.ebay.com/itm/2X-UPPER-ARM-BU ... 3m&vxp=mtr
The 1966 upper link shaft for the front is like the 320, not the later 520/521, so them will be harder to find parts for, but they may be on ebay also.
Everything I have is used, it is best to contact me directly at firstname.lastname@example.org