rearend question

[blu4X4]

we have a 70 swb chevy and have done the disc conversion on the front usinf the chevelle rotors and are now working on the rearend, converting to a 5 lug pattern. we are wondering what our options are since we have a 1970 chevelle parts car with a 12 bolt under it, since it will have the same bolt pattern as the fronts if it would work with out major modifications.. or what our other options would be without major expense