Do yourself a favor, Joe. Buy the entire 3.55 Mopar Performance differential (NEW). If you shop around hard enough, you can probably find one for $1,100 - $1,300 --> This is new. Then keep, or sell your 3.07 Diff. I've seen the stock diffs. sell from $300 - $900, depending on mileage - etc...
To swap the units should only take a pro 2 hours or so, if that. OF course, you will need the speedo calibration box to make sure your speed is accurate. Tack on another $100. And your mechanic may recommend new straps/bolts for the universal joints/axels. Another $30-$40. Bottom line: you're only going to spend a few more hundred this way, and still have the original differential. If you decide to sell it, it will cost you less than modifying your original unit.
My .02