I have a bunch of 120 negatives that I thought would be great to have as 120 positives. I know that you can do reversal processing with undeveloped negative film, but is there a sane (non-digital) method for producing 120 negatives to 120 positives?

I saw an earlier posting about the Leica ELDIA, but that's for 35mm.

Any suggestions or recommendations for a 120 process/procedure would be very appreciated.