Too bad it's been sitting in the grass. That's a rare car to still have the orig. 265 with a 3 speed stick.
I HAD A '66 BISCAYNE THAT SAT IN A GRASSY FIELD IN SOUTHERN ALBERTA FOR MANY YEARS. THE BOTTOM SIDE WAS SPOTLESS. IT HAD THE CLEANEST UNDERCARRAGE I HAVE EVER SEEN ON AN UN-RESTORED CAR. IN MOST CASES THOUGH THE GRASS WILL EAT AWAY THE BOTTOM OF THE CAR AND FRAME. I THINK WHAT SAVED MINE WAS MOST LIKELY THE PERSISTENT WINDS DOWN SOUTH KEEPING THE MOISTURE AWAY.