/ What is the best way to pick up and put in place concrete cattle guard once it has been cast, flipped over and ready to put in place?

Adding a pair of j-bolts will easily let you attach a chain, which can be lifted with your tractor.

Simply place two 8 inch J-bolts in addition to the Two 10 inch J-Bolts. The 10 inch J-Bolts are used when you remove the form from the mold. The 8 inch J-Bolts are used to transport the form in the top-side up position to the location in which you will place the form.
In order to place the 8 inch J-Bolt all you need to do is drill a small hole in the plastic where you will see a little impression and place the 8 inch J-Bolts in before you pour. The 8 inch J-Bolt will be in the gaps away from car traffic.