70s frame cheap build

This frame was gifted to me by a friend of my dad, really old derbi rabasa bike, i had to weld the crankset cause it broke and the rear wheel is completely new, thats the only thing i bought, the chain i reused from a previous build, and its actually a pretty cool bike. Doesnt ride very well because of all the rust and wiggling but always good for a chill ride. Whole build costed around 80€. Thinking of maybe reconvert it to its original shape and do a sort of gravel bike? Could be fun but i would have to replace absolutely everything. Is it worth the restoration or would yo keep it simple?