Using thicker strings for a lower tuning doesn't mean higher tension. Strings differ in tension, but using different diameters for different note ranges is meant to keep tensions roughly the same.
I use DR Black Beauties on my J, and love the way they sound. They are fairly low tension.
I use the largest B string they have (.130). This means buying the B as a single and using the bottom 3 from a four string set.
You will have to file the nut and adjust the bridge for both intonation and action for the thicker strings. Neck relief might be ok as it is, but that's for you to judge. There is no way to do this that won't require adjustments.
Now go check out the search function. It's pretty limited and generally works poorly, but you'll figure out how to make the best of it. This subject has been covered a zillion times.
