Making CC kegs into Jolly Kegs: No PRV on lid ( postimg.cc )

Being a total newbie in kegging, I recently bought some used soda kegs for cheap. Not knowing what to look for, these kegs later turned out to be of the CC variety. While this is not a bad thing per se, most accessories like the cheap Kegland spunding valves etc. only come with NC fittings, leaving me with the question of...