What Scope And Rings Would You Recommend For a FAL?

Personally...I'm not one for mounting optics on FALs, but I have a friend with a DSA Para Carbine that uses the DSA mount linked below with a Burris MTAC 1-4x and it does very well. He's had it for a while now and never experienced any issues with the mount becoming loose or otherwise losing his zero on the scope. I think he got his mount and the scope for <$500 IIRC from what he told me when I helped him install the mount (but the MTAC is certainly a cheaper optic than the Viper PST).

I'm pretty sure this is the one he ordered from DSA: FAL SA58 PARA extreme duty scope mount. 5 steel plates,10 screws & recoil guide rod

If you get in touch with Scott at Liberty Optics or Doug at CameralandNY (both Hide vendors), you should be able to get the best pricing possible on the optic and then get your rail mount and be in and done for well under your $600 max budget.