I wondered if you could just convert your old database and make it work with Fork CMS 3.7. I gave it a try...
This php script will convert your Fork CMS 3.6 database (in the best way possible) to Fork CMS 3.7 using mysql UPDATE queries. I used Kaleidoscope, a file comparing app, to see the db changes between a 3.6 dump and 3.7 mysql dump and I wrote the appropriate queries and some php code to deserialize the arrays.
Note: I've tested this script with a fresh Fork install of 3.7 where I used the database of a Fork 3.6 installation. The script converted the db and I could use the fork backend & frontend without problems. I also tried this on an existing 3.6.6 website that I made. A fresh fork install where I copied the theme & files folders, upgraded the theme to 3.7 and finally converted my old database to a working 3.7 version.