I think this is one of those questions which should be directed to the people who actually rebuild the turbos.... are some better candidates for rebuild ? Are the two you are choosing from in equal shape with regards to the things which do not get redone... ie, the fins, balance, etc.... .
Are the costs of the rebuild kits the same for each model ? Is the quality of the rebuild kit the same for both ? There are several places in Texas which rebuild them.. and we have feedback from the people who used them.... One of which is in the Waco area I believe.... a search will find those who have used them already...