front end swapped to disks, what axles do i need to swap in so my lug patterns match?

If it is an 8 1/4 it will already be big bolt pattern. It sounds like it's not, so it probably is not an 8 1/4. Can you post a pic of the back side of it? You don't mention what car this is, so once again, I have to say my subscription to my crystal ball service ran out.