I have a complete MG3 7.62x51 / 308 Conversion Kit new in packaging and covered in cosmoline for sale. I have seen the prices range from $4-700. Price is negotiable, please PM if interested trying to sell this rather quickly am open to trade's as well.
So as of now the lowest i could go for the full kit is $550-650 (considering that the barrels are ranging in from $350-500. And that RTG is out of complete kits, its unfortunate because i do remember a time where complete kits were selling for $350-500).
I would also be willing to trade the kit for a complete 8mm top cover (prefer post war), feed tray, 8mm buster bushing plus $2-300 and call it even since im not asking for an 8mm barrel and its a one for one trade on the remaining parts.