When we did a regular turkey, we would cook it breast-side down. The white meat was more juicy that way.
It doesn’t make the traditional presentation, but we always cut it up before serving.
I use a temperature probe made by Polder.
Push it in the deepest part of the breast until you hit bone. Then pull it back about an inch.
Set the probe to 160.
Pull it out of the oven when it gets to 160. It continues to cook for another half hour. Worst case is you might have to nuke some of the inner most breast meat.
I have never tried the upside down method. I end up cutting about half of it. One platter for dark meat. One for white meat.