Will it have been worth it to get those heads done,plus the the other problems you´ve had, and fuel price is an issue .Fuel
has to be used or it deteriorates and gets moisture,which settles at the bottom of the tank.Did you look at the valve seals?
probably burned oil gumming it all up.I changed the heads on mine as the originals were shot and it was cheaper to get a new set,then the oil problem came up from below,past the rings.It
seems you get one thing done and along comes the next,
but don´t we love it!