I get the feeling that you should probably scale back the build a bit. go for an explorer 8.8 with a Dana 30 for now, and an off the shelf lift kit. you can find both axles with 4.10s and then swap in late model Dana 30 shafts if the one you find is an early model. Try to find an open 8.8, as the posi isn't very good and the open diff allows you to easily install a locker.
keep it simple. get the truck running well first, and then work on the axles if needed. :thumbsup: