well is the jeep driven on the street like a DD or is it just a toy?
you could keep the vacuum disco if you want, but i would say to try and find a long side axle shaft out of a non-disco waggy, and get rid of it all together....
The lockouts and/or locker doesnt ness depend on this.... if its trail only, then you could probly be fine with the slugs still in, but if its driven on the street alot you may want to put lockouts on it...
If you are planning on regearing, this would be the time to put in a locker too.... and maybe even rebuild the axle (bearings, seals)... my advice is that if you dont have any experience with regearing axles, you may want to have someone else with experience do it or atleast help you greatly... and the prices for this ranges...
Welcome to the Jeep club and good luck with your build