how much does it cost to replace the timing chains and repair the head for bent valves on tnis engine

A lot. You are probably better off having a used engine installed.

Depending on how much you "love this car"--agree with charles automotive--but if you are mechanically inclined you could go to a salvage yard, have a "used" head pulled, get an upper engine gasket set, and do it yourself?? A problem is just how much damage was done to the piston tops when the valves hit them, sometimes it's not too bad and sometimes a valve will literally punch a hole in the piston, then the head replacement is out of the question, your talking engine replaement.