There is no requirement to change frequencies as a result of the narrowbanding process. You won't find any "conversion chart" because none exists. No one is being forced off their current frequencies, by and large they will remain exactly the same.
What needs to be changed is the amount of bandwidth the radios occupy in the spectrum when they transmit. They must occupy no greater than 12.5 kHz after the December 31st, 2012 narrowbanding deadline passes. Currently they are permitted to occupy up to 25 kHz worth of spectrum.
For the most part, you will simply see the agency add the 11K0F3E, 11K2F3E or 11K3F3E emission designators to their licenses to indicate they are narrowband compliant...on paper, at least. They still need to make sure the physical hardware is compliant.
By the way narrowbanding affects UHF also, not just VHF. All Part 90 frequencies between 150 MHz and 512 MHz are affected. Generally speaking, that means frequencies between 150 MHz through 162 MHz (excluding Railroad, Marine and Federal Government) as well as 450 MHz through 512 MHz (excluding GMRS).