All material is 3/4"
Tongue & groove is 1/4" tongue into a 1/4" groove
My thinking is to set the jig and bit as though I was using 1" stock. Use the screw called out for 3/4" material. Is my thinking correct.
Hi, George. It sounds like you are using a joinery method that I used a few years ago on a couple of projects. I'm going to try to attach some photos of the projects and samples of the joints I used.
If I recall, I used the 3/4" bit and jig settings in order to keep the screw coming out in the center of the tongue. Then, depending on the form of the board with the groove, you might have to use a slightly shorter screw to keep the point from protruding. If you use a 1" jig and bit setting the screw will exit the side of the tongue near the bottom, and it may not produce the joint strength you need.
You can test this before making the pockets. Just set the jig and bit at 3/4", insert the bit all the way into the jig, and then move the tongue portion up against the bit. You'll be able to see where the bit will exit. Then try it with a 1" setting and see what happens. Unfortunately I left my Kreg kit at my winter home in Arizona, so I can't set it up and take a picture to show you what I mean. Good luck with the project. Let me know how it works out.