If equivalent mags, accessories, etc, and condition of guns and wanting to sell, I'd offer a trade + cash of $250-350 or so premium. (+$150 to 250 above the current WASR10 and VZ2008 delta). If your gun is in very good to excellent condition, you could probably find some Romanian AK collector who'd give you $1k to $1,250 or so for it, just due to rarity and condition.
Heck, my Romy AES10B RPK that I picked up for $700 or so in the 2013-2015 time-frame (don't recall exact year offhand) now runs up to $1,500 w/ the latest imports that Century restarted this year after they haven't been imported for 5 years or so!
And if you want to PM me your email. I'll reply w/ mine, and I'm happy to post photos of handguard grip -- quite curious myself as I haven't heard of anything like that for the Vz58.