up between the cylinders the connecting rod sits (about 1/8" diameter) This rod is threaded on the end so the thermostat can attach to it. Move the connecting rod up and down to fully open (up) and close (down) the cooling vanes.
Measure the width of the little protrusion, then place the mounting bracket in your vise and carefully drill a hole of that diameter at the point you marked on the bracket.
Insert the bottom of the thermostat into the outermost hole in the new mounting bracket, then mark carefully the location of the hole that will accommodate the little protrusion that projects downward on the bottom of the thermostat.
Screw the top of the thermostat onto the threaded end of the downrod.
Loosely mount the thermostat into the outer-most hole in the bracket.
Rotate the thermostat on the downrod as necessary and insert the protrusion on the bottom into the hole you drilled in the mounting bracket. Tighten the nut to firmly attach the thermostat to the bracket and to secure the little downward piece into the hole.
Note the elongated hole in the mounting bracket. Place this hole over the stud that is projecting from the side of the crankcase. Loosely attach a washer and 13mm nut to this stud.
Pull the thermostat/mounting bracket down to fully close the cooling vanes. Don't pull it TOO tight.
Hold the mounting bracket at this point and tighten the 13mm nut to firmly attached the bracket to the side of the crankcase.
Replace the lower air duct plate that goes under the thermostat and between the right heater box and the engine, with the four bolts you took out.
The engine is cold and the thermostat is contracted completely, which means the cooling vanes are closed. Before driving the car any distance, warm it up completely and then have a look at the thermostat -- it should be fully expanded (cooling vanes fully open) directing cooling air down over the engine.