It’s not that that hard. I would do trunks, routes, IVR’s by hand.
If you have a lot of extensions you could use a spreadsheet to massage the data from the DB into a spreadsheet to import.
If you go into the mysql tool and load the asterisk DB ans start looking at the tables (select * from extensions;) you will see all your data.
Hi It will be quciker to as others have said do it by hand ,
As for extensions and DID’s use the bulk importer
as you have access to the mysql and conf files that has everything you need.
Shouldnt take taht long unless you have a lot of queues and IVRS
Do system recordings first
then import extesnions
Then create queues and Ringgroups
Then IVRS
then trunks then DID’s
Doing this normally takes a few hours to migrate a 100 user system
with teh bulkimporter creat a single test extension before doing an export so you can see what should be in the fields. and when exporting out to csv when you are finished make sure ALL fields are enclosed by quotes. same goes for teh DID import as this will have vields that have commas in them so will fail is not enclosed
yes but i have like 200 inbound DID
it was a killing job for me … imagine that and GUI is down and the system is very old !!!
so i was forced to do backup from cli then spent several hours on internet to have very old piaf to match asterisk 1.4 with very old freepbx .
then i had it on my pc as vm fresh old piaf.
then moved old backup on server that has GUI down to fresh piaf
i was able to have GUI working 
but at least i see my eyes the config
now i did it manually from old paif to freepbx
and yes i had it done in the end .
but i hope others don’t feel the pain i felt to move from asterisk 1.4 to asterisk 13
many thanks Guys